TW201921815A - Solid-state laser and inspection system using 193 nm laser - Google Patents
Solid-state laser and inspection system using 193 nm laserInfo
- Publication number
- TW201921815A TW201921815A TW108102258A TW108102258A TW201921815A TW 201921815 A TW201921815 A TW 201921815A TW 108102258 A TW108102258 A TW 108102258A TW 108102258 A TW108102258 A TW 108102258A TW 201921815 A TW201921815 A TW 201921815A
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- Prior art keywords
- harmonic
- laser
- light
- frequency
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Classifications
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- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
- H01S3/16—Solid materials
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- H01S3/1671—Solid materials characterised by a crystal matrix vanadate, niobate, tantalate
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
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- G01N2021/95676—Masks, reticles, shadow masks
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- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
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- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
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- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
- Lasers (AREA)
- Preparing Plates And Mask In Photomechanical Process (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
本發明係關於一種產生近似193奈米光且適用於光罩、倍縮光罩或晶圓檢測中之雷射系統。The present invention relates to a laser system that generates approximately 193 nanometers of light and is suitable for use in photomasks, reduction masks, or wafer inspection.
積體電路產業要求檢測工具的解析度愈來愈高以解析積體電路、光罩、太陽能電池、電荷耦合裝置等等之愈來愈小的特徵，且偵測大小為特徵大小之數量級或小於特徵大小之缺陷。短波長光源(例如，產生200奈米以下的光之源)可提供此解析度。然而，能夠提供此短波長光之光源實質上限於準分子雷射及少數固態及光纖雷射。不幸的是，此等雷射之各者具有顯著缺點。
一準分子雷射產生一紫外線光，其通常用於生產積體電路中。一準分子雷射通常在高壓條件下使用惰性氣體與反應性氣體之一組合以產生該紫外線光。產生193奈米波長光(其愈加係積體電路產業中之高度所要波長)之一習知準分子雷射使用氬(作為惰性氣體)及氟(作為反應性氣體)。不幸的是，氟係有毒的且具腐蝕性，藉此導致高的持有成本。此外，此等雷射由於其等低重複率(通常自約100 Hz至若干kHz)及極高峰值功率(其將導致在檢測期間損壞樣本)而不太適用於檢測應用。
產生次200奈米輸出之少數基於固態及光纖之雷射在此項技術中已為人所知。不幸的是，大多數此等雷射具有極低功率輸出(例如，60 mW以下)或極複雜設計，諸如兩個不同基諧波源或八個諧波產生，其等皆係複雜、不穩定、昂貴及/或不具商業吸引力。
因此，需要一種能夠產生193奈米光且克服上述缺點之雷射。The integrated circuit industry requires higher and higher resolution of detection tools to analyze the increasingly small features of integrated circuits, photomasks, solar cells, charge-coupled devices, etc., and the detection size is on the order of magnitude of the feature size or less Defects in feature size. Short-wavelength light sources (for example, sources that produce light below 200 nm) can provide this resolution. However, light sources capable of providing this short-wavelength light are essentially limited to excimer lasers and a few solid-state and fiber lasers. Unfortunately, each of these lasers has significant disadvantages.
An excimer laser produces an ultraviolet light, which is commonly used in the production of integrated circuits. An excimer laser typically uses one of an inert gas and a reactive gas under high pressure conditions to generate the ultraviolet light. One of the conventional excimer lasers that produce 193 nm wavelength light, which is a wavelength highly desired in the integrated circuit industry, uses argon (as an inert gas) and fluorine (as a reactive gas). Unfortunately, fluorine is toxic and corrosive, which leads to high holding costs. In addition, these lasers are not well suited for inspection applications due to their low repetition rate (typically from about 100 Hz to several kHz) and extremely high peak power (which will cause damage to the sample during inspection).
The few solid-state and fiber-based lasers that produce sub200nm output are known in the art. Unfortunately, most of these lasers have extremely low power output (for example, below 60 mW) or extremely complex designs, such as two different fundamental harmonic sources or eight harmonic generations, all of which are complex and unstable , Expensive and / or not commercially attractive.
Therefore, there is a need for a laser that can generate 193 nm light and overcome the above disadvantages.
根據本文所述之改良之雷射系統及相關聯技術，可由近似1064奈米之一基諧波真空波長產生大約193.368奈米之一紫外線(UV)波長。所述雷射系統及相關聯技術導致比當前用於工業中之雷射更便宜、壽命更長之雷射。此等雷射系統可用易於獲得、相對便宜的組件建構。因此，與當前市場上的UV雷射相比，所述雷射系統及相關聯技術提供明顯更佳的持有成本。
本發明描述一種用於產生大約193.368奈米波長光之雷射系統。此雷射系統可包含經組態以產生對應於大約1064奈米之一波長之一基諧波頻率之一基諧波雷射。該基諧波頻率在本文被稱為ω。一光學參數(OP)模組(諸如一光學參數振盪器或一光學參數放大器)經組態以降頻轉換該基諧波頻率且產生一OP輸出，該OP輸出係該基諧波頻率之半諧波。一五次諧波產生器模組經組態以使用該OP模組之一未耗盡基諧波頻率以產生5次諧波頻率。一混頻模組可組合該5次諧波頻率與該OP輸出以產生具有大約193.368奈米波長之一雷射輸出。
本發明描述另一種用於產生大約193.368奈米波長光之雷射系統。此雷射系統可包含經組態以產生對應於大約1064奈米之一波長之一基諧波頻率之一基諧波雷射。一五次諧波產生器模組經組態以使用該基諧波頻率以產生5次諧波頻率。一OP模組經組態以降頻轉換該五次諧波產生器模組之一未耗盡基諧波頻率以產生一OP輸出。一混頻模組可組合5次諧波頻率與該OP輸出以產生具有大約193.368奈米波長之一雷射輸出。
本發明描述又另一種用於產生大約193.368奈米波長光之雷射系統。此雷射系統可包含經組態以產生對應於大約1064奈米之一波長之一基諧波頻率之一基諧波雷射。一二次諧波產生器模組經組態以使該基諧波頻率之一部分加倍以產生2次諧波頻率。一五次諧波產生器模組經組態以使該二次諧波頻率加倍並組合一所得頻率與該二次諧波產生器模組之一未耗盡基諧波頻率以產生五次諧波頻率。一OP模組經組態以降頻轉換來自該五次諧波產生器模組之2次諧波頻率之一未耗盡部分以產生大約1.5ω之一OP信號及大約0.5ω之一OP閒頻信號，其中ω係基諧波頻率。一混頻模組可組合該5次諧波頻率與該OP閒頻信號以產生具有大約193.368奈米波長之一雷射輸出。
本發明描述又另一種用於產生大約193.368奈米波長光之雷射系統。此雷射系統可包含經組態以產生大約1064奈米之一基諧波頻率之一基諧波雷射。一二次諧波產生器模組經組態以使該基諧波頻率加倍以產生2次諧波頻率。一OP模組經組態以降頻轉換該2次諧波頻率之一部分以產生大約1.5ω之一OP信號及大約0.5ω之一OP閒頻信號，其中ω係基諧波頻率。一四次諧波產生器模組經組態以使該2次諧波頻率之另一部分加倍以產生4次諧波頻率。一混頻模組經組態以組合該四次諧波頻率與該OP信號以產生大約193.368奈米波長光之一雷射輸出。
本發明描述又另一種用於產生大約193.368奈米波長光之雷射系統。此雷射系統可包含經組態以產生大約1064奈米之一基諧波頻率之一基諧波雷射。一OP模組經組態以降頻轉換該基諧波頻率之一部分且產生一OP輸出，該OP輸出大約為該基諧波頻率之半諧波。一二次諧波產生器模組經組態以使該基諧波頻率之一部分加倍以產生2次諧波頻率。一四次諧波產生器模組經組態以使該2次諧波頻率加倍以產生4次諧波頻率。一第一混頻模組經組態以接收該4次諧波頻率及該OP輸出以產生一4.5次諧波頻率。一第二混頻模組經組態以組合該二次諧波產生器之基諧波頻率之一未耗盡部分與該4.5次諧波頻率以產生大約193.368奈米波長光之一雷射輸出。
在一些雷射系統實施例中，基諧波雷射可包括一Q切換雷射、一鎖模雷射或一連續波(CW)雷射。在一些實施例中，該基諧波雷射之雷射介質可包含一摻鐿光纖、一摻釹釔鋁石榴石晶體、一摻釹釩酸釔晶體或釩酸釓與釩酸釔之一摻釹混合物。
在一實施例中，OP模組係簡併操作，即僅存在一信號，該信號之一頻率為0.5ω。在使用簡併降頻轉換之該等實施例中，為達到最大效率，當非線性晶體性質及波長允許時較佳使用類型I降頻轉換(即，所產生的兩個光子具有相同偏光)。在另一實施例中，OP模組產生稍微不同頻率之一信號及一閒頻信號，其中一者之頻率稍微高於0.5ω且另一者之頻率稍微低於0.5ω。例如，若基諧波雷射產生1064.4奈米之一波長，則信號頻率將對應於2109.7奈米之一波長，且閒頻信號頻率將對應於2148.3奈米之一波長。
在一實施例中，OP模組可包含一OP振盪器(OPO)。在另一實施例中，OP模組可包含一OP放大器(OPA)且可包含產生所要信號波長及頻寬的光之一種子雷射。該種子雷射可包括(例如)一雷射二極體或一光纖雷射。在較佳實施例中，該種子雷射係藉由一光柵、分佈式回饋、一體積布拉格光柵或其他方式穩定化以精確地維持所要波長及頻寬。
注意，必須基於基諧波雷射之波長選擇或調整種子雷射(或一基於OPO之OP模組中之OPO波長)以達成近似193.368奈米之所要雷射系統輸出波長。例如，若所要波長係193.368奈米且基諧波雷射之中心波長係1064.4奈米，則在使用大約0.5ω之一信號頻率之該等實施例中種子雷射需要產生2109.7奈米。因為個別基諧波雷射(即使在使用相同雷射材料時)之中心波長可彼此改變零點幾奈米(取決於包含操作溫度及材料組合物變動之因素)，所以在一些較佳實施例中，種子雷射波長係可調整的。在一些實施例中，雷射系統輸出波長可需要被調整幾皮米，此可藉由將種子或OPO波長調整幾奈米而完成。
在一實施例中，五次諧波產生器模組可包含二次、四次及五次諧波產生器。該二次諧波產生器經組態以使基諧波頻率加倍以產生2次諧波頻率。該四次諧波產生器經組態以使該2次諧波頻率加倍以產生4次諧波頻率。該5次諧波產生器經組態以組合該4次諧波頻率與該二次諧波產生器之基諧波之一未耗盡部分以產生5次諧波頻率。
在另一實施例中，五次諧波產生器模組可包含二次、三次及五次諧波產生器。該二次諧波產生器經組態以使基諧波頻率加倍以產生2次諧波頻率。該三次諧波產生器經組態以組合該2次諧波頻率與該二次諧波產生器之基諧波之一未耗盡部分以產生3次諧波頻率。該五次諧波產生器經組態以組合該3次諧波頻率與該三次諧波產生器之2次諧波頻率之一未耗盡部分以產生5次諧波頻率。
在又另一實施例中，五次諧波產生器模組可包含四次及五次諧波產生器。該四次諧波產生器經組態以使2次諧波頻率加倍以產生4次諧波頻率。該五次諧波產生器經組態以接收該4次諧波頻率及基諧波頻率之一部分以產生5次諧波頻率。
在又另一實施例中，五次諧波產生器模組可包含三次及五次諧波產生器。該三次諧波產生器經組態以組合二次諧波頻率與基諧波頻率以產生3次諧波頻率。該五次諧波產生器經組態以組合該3次諧波頻率與該三次諧波產生器之一未耗盡2次諧波頻率以產生5次諧波頻率。
本發明描述一種產生大約193.368奈米波長光之方法。在此方法中，可產生大約1064奈米之一基諧波頻率。可降頻轉換此基諧波頻率以產生一OP輸出，該OP輸出係該基諧波頻率之半諧波。可使用降頻轉換之基諧波頻率之一未耗盡部分以產生5次諧波頻率。可組合該5次諧波頻率與信號頻率以產生大約193.368奈米波長光。
本發明描述另一種產生大約193.368奈米波長光之方法。在此方法中，可產生大約1064奈米之一基諧波頻率。可使用此基諧波頻率以產生一五次諧波頻率。可降頻轉換一未耗盡基諧波頻率以產生一OP輸出，該OP輸出係該基諧波頻率之半諧波。可組合該五次諧波頻率與該OP輸出以產生大約193.368奈米波長光。
本發明描述另一種產生大約193.368奈米波長光之方法。在此方法中，可產生大約1064奈米之一基諧波頻率。可使該基諧波頻率加倍以產生2次諧波頻率。可降頻轉換該2次諧波頻率之一部分以產生大約1.5ω之一OP信號及大約0.5ω之一OP閒頻信號，其中ω係基諧波頻率。可使用加倍之基諧波頻率之一未耗盡部分及降頻轉換之2次諧波頻率之一未耗盡部分以產生5次諧波頻率。可組合該5次諧波頻率與該OP閒頻信號以產生大約193.368奈米波長光。
本發明描述另一種產生大約193.368奈米波長光之方法。在此方法中，可產生大約1064奈米之一基諧波頻率。可使該基諧波頻率加倍以產生2次諧波頻率。可降頻轉換該2次諧波頻率之一部分以產生大約1.5ω之一OP信號及大約0.5ω之一OP閒頻信號，其中ω係基諧波頻率。可使二次諧波頻率之另一部分加倍以產生4次諧波頻率。可組合該4次諧波頻率與該OP信號以產生大約193.368奈米波長光。
本發明描述另一種產生大約193.368奈米波長光之方法。在此方法中，可產生大約1064奈米之一基諧波頻率。可降頻轉換該基諧波頻率之一部分以產生大約0.5ω之一OP輸出。可使該基諧波頻率之另一部分加倍以產生2次諧波頻率。可使該2次諧波頻率加倍以產生4次諧波頻率。可組合該4次諧波頻率與該OP輸出以產生一大約4.5次諧波頻率。可組合該大約4.5次諧波頻率與基諧波之又另一部分以產生大約193.368奈米波長光。
本發明描述用於檢測樣本之各種系統。此等系統可包含用於產生大約193.368奈米之一輸出輻射光束之一雷射系統。該雷射系統可包含：一基諧波雷射，其用於產生具有大約1064奈米之一對應波長之一基諧波頻率；一OP模組，其用於降頻轉換該基諧波頻率或一諧波頻率以產生一OP輸出；及複數個諧波產生器及混頻模組，其等用於產生複數個頻率。可使用該基諧波頻率、該複數個頻率及該OP輸出以產生大約193.368奈米輻射。最佳化該雷射系統以使用至少一未耗盡頻率。該等系統可進一步包含用於將輸出光束聚焦於該樣本上之構件及用於收集來自該樣本之散射光或反射光之構件。
本發明描述一種用於針對缺陷檢測一光罩、倍縮光罩或半導體晶圓之一表面之光學檢測系統。此系統可包含用於沿一光學軸發射一入射光束之一光源，該光源包含如本文所述之一雷射系統。此雷射系統可包含：一基諧波雷射，其用於產生大約1064奈米之一基諧波頻率；一光學參數(OP)模組，其用於降頻轉換該基諧波頻率或一諧波頻率以產生一OP輸出；及複數個諧波產生器及混頻模組，其等用於產生複數個頻率。可使用該基諧波頻率、該複數個頻率及該OP輸出以產生大約193.368奈米波長光。最佳化該雷射系統以使用至少一未耗盡頻率。沿該光學軸安置且包含複數個光學組件之一光學系統經組態以將入射光束分離為個別光束，所有該等個別光束在光罩、倍縮光罩或半導體晶圓之一表面上之不同位置處形成掃描光點。該等掃描光點經組態以同時掃描該表面。一透射光偵測器配置可包含對應於由該等個別光束與光罩、倍縮光罩或半導體晶圓之表面交叉引起的複數個透射光束之個別透射光束之透射光偵測器。該等透射光偵測器經配置以感測透射光之光強度。一反射光偵測器配置可包含對應於由該等個別光束與光罩、倍縮光罩或半導體晶圓之表面交叉引起的複數個反射光束之個別反射光束之反射光偵測器。該等反射光偵測器經配置以感測反射光之光強度。
本發明描述另一種用於針對缺陷檢測一光罩、倍縮光罩或半導體晶圓之一表面之光學檢測系統。此檢測系統同時照明並偵測兩個信號或影像通道。在相同感測器上同時偵測該兩個通道。當受檢測物體係透明的(例如一倍縮光罩或光罩)時，該兩個通道可包括反射及透射強度，或可包括兩種不同的照明模式，諸如入射角、偏光狀態、波長範圍或其等之某一組合。
本發明亦描述一種用於檢測一樣本之一表面之檢測系統。此檢測系統包含經組態以產生複數個光通道之一照明子系統，所產生的各光通道具有不同於至少一其他光能通道之特性。該照明子系統包含用於發射大約193.368奈米波長之一入射光束之一光源。該光源包含：一基諧波雷射，其用於產生大約1064奈米之一基諧波頻率；一OP模組，其用於降頻轉換該基諧波頻率或一諧波頻率以產生一OP輸出；及複數個諧波產生器及混頻模組，其等用於產生複數個頻率，其中使用該基諧波頻率、該複數個頻率及該OP輸出以產生大約193.368奈米波長光。最佳化該光源以使用至少一未耗盡頻率。光學器件經組態以接收該複數個光通道並將該複數個光能通道組合成一空間分離組合光束且引導該空間分離組合光束朝向該樣本。一資料擷取子系統包含經組態以偵測來自該樣本之反射光之至少一偵測器。該資料擷取子系統可經組態以將該反射光分離為對應於該複數個光通道之複數個接收通道。
本發明亦描述一種折反射檢測系統。此系統包含用於產生紫外線(UV)光之一UV光源、複數個成像子區段及一折疊鏡群組。該UV光源包含：一基諧波雷射，其用於產生大約1064奈米之一基諧波頻率；一OP模組，其用於降頻轉換該基諧波頻率或一諧波頻率以產生一OP輸出；及複數個諧波產生器及混頻模組，其等用於產生複數個頻率，其中使用該基諧波頻率、該複數個頻率及該OP輸出以產生大約193.368奈米波長光。最佳化該UV光源以使用至少一未耗盡頻率。該複數個成像子區段之各子區段可包含一聚焦透鏡群組、一場透鏡群組、一折反射透鏡群組及一變焦管透鏡群組。
該聚焦透鏡群組可包含沿系統之一光學路徑安置之複數個透鏡元件以將UV光聚焦於該系統內之一中間影像處。該聚焦透鏡群組亦可在包含一紫外線範圍中之至少一波長之一波長帶內同時提供單色像差及像差之色變動之校正。該聚焦透鏡可進一步包含經定位以接收UV光之一光束分割器。
該場透鏡群組可具有沿接近中間影像之光學路徑對準之一凈正光焦度。該場透鏡群組可包含具有不同色散之複數個透鏡元件。透鏡表面可安置在第二預定位置處且具有經選擇以對該波長帶提供包含系統之至少次級縱向色彩以及初級及次級橫向色彩之色像差之實質校正之曲率。
該折反射透鏡群組可包含至少兩個反射表面及至少一折射表面，其等經安置以形成中間影像之一實像使得結合該聚焦透鏡群組在該波長帶內實質上校正該系統之初級縱向色彩。可變焦或改變放大率而不改變其高階色像差之變焦管透鏡群組可包含沿該系統之一光學路徑安置之透鏡表面。該折疊鏡群組可經組態以容許線性變焦運動，藉此提供精細變焦及大範圍變焦。
本發明亦描述一種折反射成像系統。此系統可包含用於產生紫外線(UV)光之一UV光源。此UV光源包含：一基諧波雷射，其用於產生大約1064奈米之一基諧波頻率；一OP模組，其用於降頻轉換該基諧波頻率或一諧波頻率以產生一OP輸出；及複數個諧波產生器及混頻模組，其等用於產生複數個頻率，其中使用該基諧波頻率、該複數個頻率及信號頻率以產生大約193.368奈米波長光。最佳化該UV光源以使用至少一未耗盡頻率。亦提供調適光學器件以控制所檢測表面上之照明光束大小及輪廓。一物鏡可包含彼此成操作關係之一折反射物鏡、一聚焦透鏡群組及一變焦管透鏡區段。可提供一稜鏡以沿光學軸引導UV光法向入射至一樣本之一表面且沿一光學路徑將來自該樣本之表面特徵部之鏡面反射及來自該物鏡之光學表面之反射引導至一成像平面。
本發明亦描述一種表面檢測設備。此設備可包含用於產生大約193.368奈米之一輻射光束之一雷射系統。該雷射系統可包含：一基諧波雷射，其用於產生大約1063奈米之一基諧波頻率；一OP模組，其用於降頻轉換該基諧波頻率或一諧波頻率以產生一OP輸出；及複數個諧波產生器及混頻模組，其等用於產生複數個頻率，其中使用該基諧波頻率、該複數個頻率及信號頻率以產生大約193.368奈米輻射。最佳化該雷射系統以使用至少一未耗盡頻率。一照明系統可經組態以依相對於一表面成一非法向入射角聚焦該輻射光束以實質上在聚焦光束之一入射平面中於該表面上形成一照明線。該入射平面係藉由該聚焦光束及通過該聚焦光束且法向於該表面之一方向而界定。
本發明亦描述一種用於偵測一樣本之異常之光學系統。此光學系統包含用於產生第一光束及第二光束之一雷射系統。該雷射系統包含用於產生大約193.368奈米之一輸出輻射光束之一雷射系統。此雷射系統可包含：一基諧波雷射，其用於產生大約1064奈米之一基諧波頻率；一OP模組，其用於降頻轉換該基諧波頻率或一諧波頻率以產生一OP輸出；及複數個諧波產生器及混頻模組，其等用於產生複數個頻率，其中使用該基諧波頻率、該複數個頻率及該OP輸出以產生大約193.368奈米輻射。最佳化該雷射系統以使用至少一未耗盡頻率。該輸出光束可使用標準組件分割成該第一光束及該第二光束。第一光學器件可沿一第一路徑將該第一光束引導至該樣本之一表面上之一第一光點上。第二光學器件可沿一第二路徑將該第二光束引導至該樣本之一表面上之一第二光點上。該第一路徑及該第二路徑與該樣本之表面成不同的入射角。集光光學器件可包含自該樣本表面上之第一光點或第二光點接收散射輻射且源自該第一光束或該第二光束並將該散射輻射聚焦至一第一偵測器之一彎曲鏡表面。該第一偵測器回應於藉由該彎曲鏡表面聚焦至該第一偵測器上之輻射提供一單個輸出值。可提供一儀器，該儀器引起該第一光束及該第二光束與該樣本之間之相對運動使得跨該樣本之表面掃描該等光點。According to the improved laser system and related technologies described herein, approximately one 193.368 nanometer ultraviolet (UV) wavelength can be generated from approximately a base harmonic vacuum wavelength of 1064 nanometers. The laser system and associated technologies result in lasers that are cheaper and have a longer life than lasers currently used in industry. These laser systems can be constructed with readily available and relatively inexpensive components. Therefore, the laser system and associated technologies provide significantly better holding costs compared to UV lasers currently on the market.
The present invention describes a laser system for generating light at a wavelength of about 193.368 nanometers. This laser system may include a fundamental harmonic laser configured to generate a fundamental harmonic frequency corresponding to a wavelength of approximately 1064 nanometers. This fundamental harmonic frequency is referred to herein as ω. An optical parameter (OP) module (such as an optical parameter oscillator or an optical parameter amplifier) is configured to down-convert the fundamental harmonic frequency and generate an OP output that is a half-harmonic of the fundamental harmonic frequency wave. A fifth harmonic generator module is configured to use an undepleted fundamental harmonic frequency of one of the OP modules to generate a fifth harmonic frequency. A mixing module can combine the 5th harmonic frequency with the OP output to generate a laser output with a wavelength of about 193.368 nanometers.
The present invention describes another laser system for generating light at a wavelength of about 193.368 nanometers. This laser system may include a fundamental harmonic laser configured to generate a fundamental harmonic frequency corresponding to a wavelength of approximately 1064 nanometers. A fifth harmonic generator module is configured to use the fundamental harmonic frequency to generate a fifth harmonic frequency. An OP module is configured to down-convert an undepleted fundamental harmonic frequency of one of the fifth harmonic generator modules to generate an OP output. A mixing module can combine the 5th harmonic frequency with the OP output to generate a laser output with a wavelength of about 193.368 nanometers.
The present invention describes yet another laser system for generating light at a wavelength of about 193.368 nanometers. This laser system may include a fundamental harmonic laser configured to generate a fundamental harmonic frequency corresponding to a wavelength of approximately 1064 nanometers. A second harmonic generator module is configured to double a portion of the fundamental harmonic frequency to generate a second harmonic frequency. A fifth harmonic generator module is configured to double the second harmonic frequency and combine an obtained frequency with an undepleted fundamental harmonic frequency of one of the second harmonic generator modules to generate a fifth harmonic Wave frequency. An OP module is configured to down-convert an undepleted portion of the second harmonic frequency from the fifth harmonic generator module to generate an OP signal of about 1.5ω and an OP idle frequency of about 0.5ω Signal, where ω is the fundamental harmonic frequency. A mixing module can combine the 5th harmonic frequency with the OP idle frequency signal to generate a laser output having a wavelength of approximately 193.368 nanometers.
The present invention describes yet another laser system for generating light at a wavelength of about 193.368 nanometers. This laser system may include a fundamental harmonic laser configured to generate a fundamental harmonic frequency of approximately 1064 nanometers. A second-harmonic generator module is configured to double the fundamental harmonic frequency to generate a second-harmonic frequency. An OP module is configured to down-convert a part of the second harmonic frequency to generate an OP signal of about 1.5ω and an OP idle frequency signal of about 0.5ω, where ω is the fundamental harmonic frequency. A fourth-harmonic generator module is configured to double the other part of the second-harmonic frequency to generate a fourth-harmonic frequency. A mixing module is configured to combine the fourth harmonic frequency with the OP signal to generate a laser output of one of the wavelengths of about 193.368 nanometers.
The present invention describes yet another laser system for generating light at a wavelength of about 193.368 nanometers. This laser system may include a fundamental harmonic laser configured to generate a fundamental harmonic frequency of approximately 1064 nanometers. An OP module is configured to down-convert a portion of the fundamental harmonic frequency and generate an OP output, the OP output is approximately a half harmonic of the fundamental harmonic frequency. A second harmonic generator module is configured to double a portion of the fundamental harmonic frequency to generate a second harmonic frequency. A fourth harmonic generator module is configured to double the second harmonic frequency to generate a fourth harmonic frequency. A first mixing module is configured to receive the 4th harmonic frequency and the OP output to generate a 4.5th harmonic frequency. A second mixing module is configured to combine an undepleted portion of one of the fundamental harmonic frequencies of the second harmonic generator with the 4.5th harmonic frequency to produce a laser output of approximately 193.368 nm wavelength light .
In some laser system embodiments, the fundamental harmonic laser may include a Q-switched laser, a mode-locked laser, or a continuous wave (CW) laser. In some embodiments, the harmonic laser-based laser medium may include an erbium-doped fiber, a neodymium-doped yttrium aluminum garnet crystal, a neodymium-doped yttrium vanadate crystal, or one of erbium vanadate and yttrium vanadate. Neodymium mixture.
In one embodiment, the OP module is degenerate, that is, there is only one signal, and one of the signals has a frequency of 0.5ω. In these embodiments using degenerate down-conversion, for maximum efficiency, type I down-conversion is preferably used when the nature of the non-linear crystal and wavelength allows (ie, the two photons produced have the same polarization). In another embodiment, the OP module generates a signal with a slightly different frequency and an idler signal. The frequency of one of them is slightly higher than 0.5ω and the frequency of the other is slightly lower than 0.5ω. For example, if the fundamental harmonic laser produces a wavelength of 1064.4 nanometers, the signal frequency will correspond to a wavelength of 2109.7 nanometers, and the idle frequency signal frequency will correspond to a wavelength of 2148.3 nanometers.
In one embodiment, the OP module may include an OP oscillator (OPO). In another embodiment, the OP module may include an OP amplifier (OPA) and may include a seed laser that generates light of a desired signal wavelength and bandwidth. The seed laser may include, for example, a laser diode or a fiber optic laser. In a preferred embodiment, the seed laser is stabilized by a grating, distributed feedback, a volume Bragg grating, or other methods to accurately maintain the desired wavelength and bandwidth.
Note that the seed laser (or the OPO wavelength in an OPO-based OP module) must be selected or adjusted based on the wavelength of the fundamental harmonic laser to achieve a desired laser system output wavelength of approximately 193.368 nm. For example, if the desired wavelength is 193.368 nanometers and the center wavelength of the fundamental harmonic laser is 1064.4 nanometers, the seed laser needs to generate 2109.7 nanometers in these embodiments using a signal frequency of about 0.5ω. Because the center wavelengths of individual fundamental harmonic lasers (even when using the same laser material) can vary by a few tenths of a nanometer (depending on factors including operating temperature and changes in material composition), in some preferred embodiments The seed laser wavelength is adjustable. In some embodiments, the laser system output wavelength may need to be adjusted by a few picometres, which may be done by adjusting the seed or OPO wavelength by a few nanometres.
In an embodiment, the fifth harmonic generator module may include second, fourth, and fifth harmonic generators. The second harmonic generator is configured to double the fundamental harmonic frequency to generate a second harmonic frequency. The fourth harmonic generator is configured to double the second harmonic frequency to generate a fourth harmonic frequency. The 5th harmonic generator is configured to combine the 4th harmonic frequency with an undepleted portion of one of the fundamental harmonics of the 2nd harmonic generator to generate a 5th harmonic frequency.
In another embodiment, the fifth harmonic generator module may include second, third, and fifth harmonic generators. The second harmonic generator is configured to double the fundamental harmonic frequency to generate a second harmonic frequency. The third harmonic generator is configured to combine the second harmonic frequency with an undepleted portion of one of the fundamental harmonics of the second harmonic generator to generate a third harmonic frequency. The fifth harmonic generator is configured to combine an undepleted portion of the third harmonic frequency with one of the second harmonic frequencies of the third harmonic generator to generate a fifth harmonic frequency.
In yet another embodiment, the fifth harmonic generator module may include fourth and fifth harmonic generators. The fourth harmonic generator is configured to double the second harmonic frequency to generate a fourth harmonic frequency. The fifth harmonic generator is configured to receive a portion of the fourth harmonic frequency and a fundamental harmonic frequency to generate a fifth harmonic frequency.
In yet another embodiment, the fifth harmonic generator module may include third and fifth harmonic generators. The third harmonic generator is configured to combine a second harmonic frequency and a fundamental harmonic frequency to generate a third harmonic frequency. The fifth harmonic generator is configured to combine the third harmonic frequency with an undepleted second harmonic frequency of one of the third harmonic generators to generate a fifth harmonic frequency.
The present invention describes a method for generating light at a wavelength of about 193.368 nanometers. In this method, a fundamental harmonic frequency of about 1064 nanometers can be generated. The fundamental harmonic frequency can be down-converted to generate an OP output, the OP output is a half harmonic of the fundamental harmonic frequency. An undepleted portion of one of the fundamental harmonic frequencies of the down-conversion can be used to generate the fifth harmonic frequency. The 5th harmonic frequency and the signal frequency can be combined to produce light at a wavelength of approximately 193.368 nanometers.
The present invention describes another method of generating light at a wavelength of about 193.368 nanometers. In this method, a fundamental harmonic frequency of about 1064 nanometers can be generated. This fundamental harmonic frequency can be used to generate one or five harmonic frequencies. An undepleted fundamental harmonic frequency can be down-converted to generate an OP output, the OP output is a half harmonic of the fundamental harmonic frequency. The fifth harmonic frequency can be combined with the OP output to produce approximately 193.368 nanometer wavelength light.
The present invention describes another method of generating light at a wavelength of about 193.368 nanometers. In this method, a fundamental harmonic frequency of about 1064 nanometers can be generated. This fundamental harmonic frequency can be doubled to produce a second harmonic frequency. A part of the second harmonic frequency can be down-converted to generate an OP signal of about 1.5ω and an OP idle frequency signal of about 0.5ω, where ω is the fundamental harmonic frequency. An undepleted portion of the doubled harmonic frequency and an undepleted portion of the 2nd harmonic frequency of the down-conversion can be used to generate the 5th harmonic frequency. The 5th harmonic frequency can be combined with the OP idle frequency signal to generate approximately 193.368 nanometer wavelength light.
The present invention describes another method of generating light at a wavelength of about 193.368 nanometers. In this method, a fundamental harmonic frequency of about 1064 nanometers can be generated. This fundamental harmonic frequency can be doubled to produce a second harmonic frequency. A part of the second harmonic frequency can be down-converted to generate an OP signal of about 1.5ω and an OP idle frequency signal of about 0.5ω, where ω is the fundamental harmonic frequency. The other part of the second harmonic frequency can be doubled to produce the fourth harmonic frequency. The 4th harmonic frequency can be combined with the OP signal to generate light at a wavelength of approximately 193.368 nanometers.
The present invention describes another method of generating light at a wavelength of about 193.368 nanometers. In this method, a fundamental harmonic frequency of about 1064 nanometers can be generated. A portion of this fundamental harmonic frequency can be down-converted to produce an OP output of approximately 0.5ω. The other part of the fundamental harmonic frequency can be doubled to produce a second harmonic frequency. This second harmonic frequency can be doubled to produce a fourth harmonic frequency. The 4th harmonic frequency can be combined with the OP output to generate a 4.5th harmonic frequency. Another portion of the approximately 4.5th harmonic frequency and the fundamental harmonic can be combined to produce approximately 193.368 nanometer wavelength light.
The present invention describes various systems for detecting a sample. Such systems may include a laser system for generating an output radiation beam of approximately 193.368 nanometers. The laser system may include: a fundamental harmonic laser for generating a fundamental harmonic frequency having a corresponding wavelength of approximately 1064 nm; and an OP module for down-converting the fundamental harmonic frequency Or a harmonic frequency to generate an OP output; and a plurality of harmonic generators and mixing modules, which are used to generate a plurality of frequencies. The fundamental harmonic frequency, the plurality of frequencies, and the OP output can be used to generate approximately 193.368 nanometer radiation. The laser system is optimized to use at least one undepleted frequency. The systems may further include means for focusing an output beam on the sample and means for collecting scattered or reflected light from the sample.
The present invention describes an optical inspection system for detecting a surface of a photomask, a reticle, or a semiconductor wafer for defects. The system may include a light source for emitting an incident light beam along an optical axis, the light source including a laser system as described herein. The laser system may include: a fundamental harmonic laser for generating a fundamental harmonic frequency of about 1064 nm; and an optical parameter (OP) module for down-converting the fundamental harmonic frequency or A harmonic frequency to generate an OP output; and a plurality of harmonic generators and a mixing module, which are used to generate a plurality of frequencies. The fundamental harmonic frequency, the plurality of frequencies, and the OP output can be used to generate approximately 193.368 nanometer wavelength light. The laser system is optimized to use at least one undepleted frequency. An optical system disposed along the optical axis and containing a plurality of optical components is configured to separate an incident light beam into individual light beams, all of which are different on a surface of a photomask, a reduction mask, or a semiconductor wafer Scanning spots are formed at the positions. The scanning spots are configured to scan the surface simultaneously. A transmitted light detector configuration may include a transmitted light detector corresponding to the individual transmitted light beams of the plurality of transmitted light beams caused by the intersection of the individual light beams with the surface of the reticle, reduction mask, or semiconductor wafer. The transmitted light detectors are configured to sense the light intensity of the transmitted light. A reflected light detector configuration may include a reflected light detector corresponding to the individual reflected light beams of the plurality of reflected light beams caused by the intersection of the individual light beams with the surface of the reticle, reduction mask, or semiconductor wafer. The reflected light detectors are configured to sense the light intensity of the reflected light.
The present invention describes another optical inspection system for detecting a surface of a photomask, a reticle, or a semiconductor wafer for defects. This detection system illuminates and detects two signal or video channels simultaneously. The two channels are detected simultaneously on the same sensor. When the system of the object to be detected is transparent (e.g., a double reduction mask or reticle), the two channels may include reflection and transmission intensity, or may include two different illumination modes, such as an angle of incidence, a polarization state, and a wavelength range. Or some combination thereof.
The invention also describes a detection system for detecting a surface of a sample. The detection system includes an illumination subsystem configured to generate one of a plurality of light channels, and each light channel generated has characteristics different from at least one other light energy channel. The lighting subsystem includes a light source for emitting an incident light beam at a wavelength of approximately 193.368 nanometers. The light source includes: a fundamental harmonic laser, which is used to generate a fundamental harmonic frequency of about 1064 nm; an OP module, which is used to down-convert the fundamental harmonic frequency or a harmonic frequency to generate a OP output; and a plurality of harmonic generators and mixing modules, which are used to generate a plurality of frequencies, wherein the fundamental harmonic frequency, the plurality of frequencies, and the OP output are used to generate approximately 193.368 nm wavelength light. The light source is optimized to use at least one undepleted frequency. The optical device is configured to receive the plurality of optical channels and combine the plurality of optical energy channels into a spatially separated combined light beam and guide the spatially separated combined light beam toward the sample. A data acquisition subsystem includes at least one detector configured to detect reflected light from the sample. The data acquisition subsystem may be configured to separate the reflected light into a plurality of receiving channels corresponding to the plurality of optical channels.
The invention also describes a reflection detection system. The system includes a UV light source for generating ultraviolet (UV) light, a plurality of imaging sub-segments, and a group of folding mirrors. The UV light source includes: a fundamental harmonic laser, which is used to generate a fundamental harmonic frequency of about 1064 nm; and an OP module, which is used to down-convert the fundamental harmonic frequency or a harmonic frequency to generate An OP output; and a plurality of harmonic generators and mixing modules, which are used to generate a plurality of frequencies, wherein the fundamental harmonic frequency, the plurality of frequencies, and the OP output are used to generate approximately 193.368 nm wavelength light . The UV light source is optimized to use at least one undepleted frequency. Each of the plurality of imaging sub-sections may include a focusing lens group, a field lens group, a fold reflection lens group, and a zoom tube lens group.
The focusing lens group may include a plurality of lens elements arranged along an optical path of the system to focus the UV light at an intermediate image in the system. The focusing lens group can also provide correction of monochrome aberrations and color variations of aberrations in a wavelength band including at least one wavelength in an ultraviolet range. The focusing lens may further include a beam splitter positioned to receive UV light.
The field lens group may have a net positive power aligned along an optical path near the intermediate image. The field lens group may include a plurality of lens elements having different dispersions. The lens surface may be disposed at a second predetermined position and have a curvature selected to provide a substantial correction to the wavelength band including chromatic aberrations of at least the secondary longitudinal colors and primary and secondary lateral colors of the system.
The refracting lens group may include at least two reflecting surfaces and at least one refractive surface, which are arranged to form a real image of an intermediate image so that the primary longitudinal direction of the system is substantially corrected in the wavelength band by combining the focusing lens group. color. A group of zoom tube lenses that can zoom or change the magnification without changing its higher-order chromatic aberrations can include lens surfaces that are placed along one of the optical paths of the system. The group of folding mirrors can be configured to allow linear zoom motion, thereby providing fine zoom and wide range zoom.
The invention also describes a refracting imaging system. This system may include a UV light source for generating ultraviolet (UV) light. The UV light source includes: a fundamental harmonic laser, which is used to generate a fundamental harmonic frequency of about 1064 nm; and an OP module, which is used to down-convert the fundamental harmonic frequency or a harmonic frequency to generate An OP output; and a plurality of harmonic generators and mixing modules, which are used to generate a plurality of frequencies, wherein the fundamental harmonic frequency, the plurality of frequencies, and the signal frequency are used to generate approximately 193.368 nanometer wavelength light. The UV light source is optimized to use at least one undepleted frequency. Optics are also provided to control the size and profile of the illumination beam on the surface being inspected. An objective lens may include a fold-reflection objective lens, a focusing lens group, and a zoom tube lens section in an operational relationship with each other. It is possible to provide a guide for directing UV light incident on a surface of a specimen along an optical axis and guiding an specular reflection from a surface feature of the sample and an reflection from an optical surface of the objective lens along an optical path to an imaging flat.
The invention also describes a surface inspection device. This device may include a laser system for generating a radiation beam of approximately 193.368 nanometers. The laser system may include: a fundamental harmonic laser for generating a fundamental harmonic frequency of about 1063 nanometers; and an OP module for down-converting the fundamental harmonic frequency or a harmonic frequency To generate an OP output; and a plurality of harmonic generators and mixing modules, which are used to generate a plurality of frequencies, wherein the fundamental harmonic frequency, the plurality of frequencies, and a signal frequency are used to generate approximately 193.368 nanometer radiation . The laser system is optimized to use at least one undepleted frequency. An illumination system can be configured to focus the radiation beam at an illegally incident angle relative to a surface to form an illumination line on the surface substantially in one of the incident planes of the focused beam. The incident plane is defined by the focused beam and a direction passing through the focused beam and normal to the surface.
The invention also describes an optical system for detecting an abnormality of a sample. The optical system includes a laser system for generating one of a first light beam and a second light beam. The laser system includes a laser system for generating an output radiation beam of approximately 193.368 nanometers. The laser system may include: a fundamental harmonic laser for generating a fundamental harmonic frequency of about 1064 nm; and an OP module for down-converting the fundamental harmonic frequency or a harmonic frequency To generate an OP output; and a plurality of harmonic generators and mixing modules, which are used to generate a plurality of frequencies, wherein the fundamental harmonic frequency, the plurality of frequencies and the OP output are used to generate approximately 193.368 nm radiation. The laser system is optimized to use at least one undepleted frequency. The output beam can be split into the first beam and the second beam using standard components. The first optical device can guide the first light beam to a first light spot on a surface of the sample along a first path. The second optical device can guide the second light beam to a second light spot on a surface of the sample along a second path. The first path and the second path have different incidence angles with the surface of the sample. The light collection optics may include receiving scattered radiation from a first light spot or a second light spot on the surface of the sample and originating from the first light beam or the second light beam and focusing the scattered radiation to a first detector. A curved mirror surface. The first detector provides a single output value in response to radiation focused on the first detector by the curved mirror surface. An instrument may be provided that causes the relative motion between the first and second light beams and the sample to scan the light spots across the surface of the sample.
相關申請案
本申請案主張標題為「Solid-State 193 nm Laser And An Inspection System Using A Solid-State 193 nm Laser」且申請於2012年5月22日之美國臨時申請案61/650,349之優先權，該案係以引用方式併入本文。
根據本文所述之一改良雷射技術及雷射系統，可由近似1063.5奈米(例如，近似1063.52奈米或在另一實例中介於約1064.0奈米與約1064.6奈米之間)之一基諧波真空波長產生大約193.4奈米之一紫外線(UV)波長(例如近似193.368奈米之一真空波長)。在本文無限定地給定一波長之情況下，假定該波長指代光的真空波長。
本發明之每項實施例在一個以上頻率轉換級中使用至少一頻率。一般而言，頻率轉換級並未完全耗盡其等輸入光，此可有利地在本文所述之改良之雷射系統中得到充分利用。本發明之較佳實施例分離出至少一級之一輸入波長之一未耗盡部分且重定向該未耗盡部分以於另一級中使用。頻率轉換及混頻係非線性程序。轉換效率隨著輸入功率位準增加而增加。例如，基諧波雷射之整個輸出可首先被引導至一級(諸如一二次諧波產生器)以最大化該級之效率且最小化用於該級之晶體之長度(及因此成本)。在此實例中，基諧波之未耗盡部分將被引導至另一級(諸如一五次諧波產生器或一光學參數模組)以於該級中使用。
分離出一未耗盡輸入頻率且將其單獨引導至另一級而非容許其與該級之輸出共同傳播之一優點在於：可針對各頻率單獨控制光學路徑長度，藉此確保脈衝同時到達。另一優點在於：可針對各個別頻率最佳化塗層及光學組件而非在兩種頻率的需要之間損及塗層及光學組件。特定言之，一二次諧波產生器或四次諧波產生器之輸出頻率相對於輸入頻率將具有一垂直偏光。用於允許一頻率以最小反射進入之布魯斯特窗(Brewster window)通常將針對另一頻率而具有一高反射率，這係因為該另一頻率之偏光對該窗而言係錯誤的。
本發明之較佳實施例對產生深UV波長(諸如短於約350奈米之波長)之頻率轉換級及混頻級使用保護環境。在2012年10月30日頒予Armstrong之標題為「Enclosure for controlling the environment of optical crystals」之美國專利8,298,335及2013年1月24日由Dribinski等人發表之標題為「Laser With High Quality, Stable Output Beam, And Long Life High Conversion Efficiency Non-Linear Crystal」之美國公開申請案2013/0021602中描述合適的保護環境，該兩個申請案皆係以引用方式併入本文。特定言之，布魯斯特窗可用於此等環境以容許輸入及輸出頻率進入或離開。單獨引導各頻率容許視需要使用不同的布魯斯特窗或塗層以最小化雷射系統內的損耗及雜散光。
下文所述之改良之雷射技術及雷射系統使用半諧波以使基諧波長除以5.5(即，使基諧波頻率乘以5.5)。注意，使一波長除以N亦可被描述為使其對應頻率乘以N，其中N係任何數字(無論整數或分數)。如圖式中使用，ω指定為基諧波頻率。例如，圖1A至圖1C以***括號指示藉由例示性雷射系統之各種組件產生之光波長(相對於基諧波頻率)，例如(ω)、(0.5ω)、(1.5ω)、(2ω)、(4ω)、(4.5ω)及(5ω)。注意，可使用類似符號指示基諧波頻率之一諧波，例如，五次諧波等於5ω。0.5ω、1.5ω及4.5ω之諧波亦可被稱為半諧波。注意在一些實施例中，使用稍微自0.5ω移位之頻率而非確切使用0.5ω之頻率。被描述為大約0.5ω、大約1.5ω等等之頻率可取決於實施例而指代確切半諧波或稍微移位頻率。為在描述該等圖式之元件時便於引用，數字表示法(例如，「5次諧波」)指代頻率本身，而字詞表示法(例如，「五次諧波」)指代產生該頻率之組件。
圖1A圖解說明用於產生大約193.4奈米之一紫外線(UV)波長之一例示性雷射系統100。在此實施例中，雷射系統100包含產生一基諧波頻率ω(即，基諧波102)之光之一基諧波雷射101。在一實施例中，該基諧波頻率ω可為對應於近似1064奈米之一紅外線波長之頻率。例如，在一些較佳實施例中，基諧波雷射101可發射實質上1063.52奈米之一波長。在其他實施例中，基諧波雷射101可發射介於約1064.0奈米與約1064.6奈米之間之一波長。基諧波雷射101可藉由使用一合適的雷射介質(諸如摻釹釔鋁石榴石(Nd:YAG)或摻釹釩酸釔)之一雷射而實施。釩酸釓與釩酸釔之一摻釹混合物(例如，該兩種釩酸鹽之一大約50:50混合物)係另一合適的雷射介質，其在近似1063.5奈米之波長下可具有高於Nd:YAG或摻釹釩酸釔之增益。摻鐿光纖雷射係可用以產生近似1063.5奈米之一波長之雷射光之另一替代物。可經修改或調諧以在大約1063.5奈米波長下運作之雷射可作為脈衝雷射(Q切換或鎖模)或連續波(CW)雷射購得。此等可修改雷射之例示性製造商包含Coherent Inc.(例如，具有80兆赫茲及120兆赫茲之重複率之Paladin族中的模型)、Newport Corporation(例如，Explorer族中的模型)及其他製造商。可與基諧波雷射101一起使用以控制波長及頻寬之技術包含分佈式回饋或使用諸如光纖布拉格光柵、繞射光柵或標準量具之波長選擇性裝置。在其他實施例中，諸如剛剛列舉之一市售雷射係以其標準波長操作，標準波長通常係介於約1064.0奈米與約1064.6奈米之間之一波長。在此等實施例中，信號或閒頻信號頻率(參見下文)可自確切0.5ω移位以產生所要輸出波長。
注意，基諧波雷射101判定輸出光之總體穩定性及頻寬。在低功率位準及中等功率位準(諸如約1毫瓦至幾十瓦之位準)下，通常更易於達成穩定的窄頻寬雷射。穩定化波長且縮小較高功率或較短波長雷射之頻寬更為複雜且昂貴。基諧波雷射101之雷射功率位準可在毫瓦至幾十瓦或更大之範圍中。因此，可容易地穩定化基諧波雷射101。
基諧波102可經引導朝向一光學參數振盪器(OPO)或一光學參數放大器(OPA)。以光學頻率振盪之一OPO藉由二階非線性光學相互作用將其輸入頻率降頻轉換為一或兩個輸出頻率。在兩個輸出頻率之情況中，產生一「信號」頻率及一「閒頻信號」頻率(在圖式中展示為「信號+閒頻信號」)。該兩個輸出頻率之總和等於輸入頻率。在一輸出頻率(稱為一簡併OP模組)之情況中，信號頻率與閒頻信號頻率相同且因此難以針對所有實踐目的進行區分。一OPA係使用一光學參數放大程序放大輸入波長之種子(或輸入)光之一雷射光源。為簡單起見，本文使用一般術語「OP模組」以指代一OPO或一OPA。
在雷射系統100中，一OP模組103將基諧波102之一部分降頻轉換為一簡併輸出頻率(大約0.5ω)107。因此，在簡併情況中，藉由OP模組103降頻轉換之光輸出的波長係兩倍於基諧波102的波長。例如，若基諧波102具有1063.5奈米之一波長，則信號107之波長係2127奈米。在一些實施例中，OP模組103可包含一非線性晶體，諸如週期極化鈮酸鋰、掺雜氧化鎂之鈮酸鋰或磷酸鈦氧鉀(KTP)。在一些實施例中，OP模組103可包含一低功率雷射，諸如二極體雷射或一低功率光纖雷射。
注意，在降頻轉換程序中僅耗盡基諧波102之部分。實際上，一般而言，OP模組及諧波產生器並未完全耗盡其等輸入光，此可有利地在本文所述之改良之雷射系統中得到充分利用。例如，OP模組103之一未耗盡基諧波104可被引導至一五次諧波(5ω)產生器模組105，其包括若干頻率轉換級及混頻級以由該基諧波產生5次諧波(下文參考圖2A及圖2B更詳細描述)。
類似地，在一替代性實施例中，基諧波102’可首先被引導至該五次諧波產生器模組105以產生一5次諧波106，且在產生該5次諧波106期間未耗盡的基諧波102’(未耗盡基諧波104’)可被引導至OP模組103以降頻轉換至輸出頻率107。
可在一混頻模組108中組合(即，混合)五次諧波產生器模組105之輸出(即，5次諧波106)與輸出頻率107。在一實施例中，混頻模組108可包含(相同類型之)一或多個非線性晶體，諸如β-硼酸鋇(BBO)、三硼酸鋰(LBO)或氫退火硼酸鋰銫(CLBO)晶體。混頻模組108產生具有大約5.5ω之一頻率且具有193.368奈米之一對應波長之一雷射輸出109(即，基諧波長除以大約5.5)。
使用類型I簡併降頻轉換之優點係：在產生一非所要波長或偏光期間不浪費功率。若在5.5倍於近似193.368奈米之所要輸出波長之一波長下具有足夠功率之一基諧波雷射容易以合理成本獲得，則包含簡併降頻轉換之實施例可係較佳的。非簡併降頻轉換之優點係：可容易以幾十瓦或100瓦之功率位準獲得波長介於約1064.0奈米與約1064.6奈米之間的雷射，而當前不容易以此等功率位準獲得實質上1063.5奈米之波長的雷射。非簡併降頻轉換容許容易地獲得大功率雷射以產生接近193.368奈米之任何所要輸出波長。
圖1B圖解說明用於產生大約193.368奈米之一UV波長之另一例示性雷射系統130。在此實施例中，在一基諧波頻率ω下操作之一基諧波雷射110產生基諧波111。在一實施例中，頻率ω可對應於大約1063.5奈米之一波長，或在另一實施例中，對應於介於約1064.0奈米與約1064.6奈米之間之一波長。基諧波111可被引導至一二次諧波產生器模組112，其使基諧波111加倍以產生一2次諧波113。來自二次諧波產生器模組112之基諧波111之一未耗盡部分(即，未耗盡基諧波121)可被引導至一五次諧波產生器模組116。該2次諧波113可被引導至一OP模組114。在一些實施例中，OP模組114可包含一非線性晶體，諸如週期極化鈮酸鋰、掺雜氧化鎂之鈮酸鋰或KTP。在一些實施例中，OP模組114可包含一低功率雷射，諸如二極體雷射或一低功率光纖雷射。
在一較佳實施例中，OP模組114產生包含大約1.5ω之一信號及大約0.5ω之一閒頻信號之輸出頻率120。注意因為該信號及該閒頻信號之波長在此實施例中完全不同，所以可使用(例如)二向色塗層、稜鏡或光柵容易地分離該信號及該閒頻信號。在一些實施例中，該信號及該閒頻信號具有實質上正交偏光且因此可藉由(例如)一偏光光束分割器分離。在雷射系統130中，0.5ω或大約0.5ω的閒頻信號係所關注的頻率分量。例如，若該基諧波111之波長為1063.5奈米，則藉由OP模組114降頻轉換之與該閒頻信號相關聯之光輸出之波長係2127奈米，其係兩倍於基諧波102之波長。在另一實例中，若基諧波102之波長為1064.4奈米且所要輸出波長係193.368奈米，則該閒頻信號波長將為2109.7奈米。
注意在其他實施例中，無須分離信號與閒頻信號，這係因為在混頻模組118中僅所要波長適當地相位匹配。即，混頻模組118可經組態以接收該信號及該閒頻信號二者，但是實際上僅使用該閒頻信號(其為0.5ω)。因為在此等實施例中非所要波長係大約710奈米之一波長，所以在此等波長下並未顯著吸收適用於混頻模組118中之大部分非線性晶體，且因此非所要波長不太可能引起顯著加熱或其他非所要效應。
五次諧波產生器模組116組合來自OP模組114之一未耗盡2次諧波115與未耗盡基諧波121以產生一5次諧波117(參見，例如圖3A及圖3B，例示性五次諧波產生器模組)。一混頻模組118混合5次諧波117與輸出頻率120之閒頻信號部分以產生大約5.5ω之一雷射輸出119。在一實施例中，混頻模組118可包含一或多個非線性晶體，諸如β-硼酸鋇(BBO)、LBO或CLBO晶體。
注意，以類似於圖1A中針對基諧波102及102’圖解說明之一方式，在雷射系統130之一些實施例中，2次諧波113’可首先被引導至該五次諧波產生器模組116，且該2次諧波之未耗盡部分115’被引導至OP模組114，如虛線所示。
圖1C圖解說明用於產生大約193.4奈米之一UV波長之又另一例示性雷射系統140。在此實施例中，在一頻率ω下操作之一基諧波雷射122產生一基諧波123。在此實施例中，頻率ω可對應於大約1063.5奈米之一波長或介於約1064.0奈米與約1064.6奈米之間之一波長。
基諧波123可被引導至一二次諧波產生器模組124，其使基諧波123加倍以產生一2次諧波125。該2次諧波125被引導至一OP模組126。在一實施例中，OP模組126產生包含大約1.5ω之一信號及大約0.5ω之一閒頻信號之輸出頻率129。在一些實施例中，OP模組126可包含一非線性晶體，諸如週期極化鈮酸鋰、掺雜氧化鎂之鈮酸鋰或KTP。在其他實施例中，OP模組126可包含一低功率雷射，諸如二極體雷射或一低功率光纖雷射。如下文所論述，輸出頻率129之信號部分(大約1.5ω)係混頻模組131所關注的頻率分量。
OP模組126之一未耗盡2次諧波127可被引導至一四次諧波產生器模組128。四次諧波產生器模組128使未耗盡2次諧波127加倍以產生一4次諧波133。
在一些實施例中，來自該二次諧波產生器124之2次諧波125’首先被引導至該四次諧波產生器128，且來自該四次諧波產生器128之未耗盡2次諧波127’被引導至該OP模組126以用於降頻轉換。
在雷射系統140中，混頻模組131組合輸出頻率129之信號部分與4次諧波133以產生具有大約5.5ω之一波長之一雷射輸出132。如上所提及，由於信號與閒頻信號之頻率差，該閒頻信號在由混頻模組131接收之前無須與該信號分離。在一實施例中，混頻模組131可包含在大約120°C之一溫度下操作以組合該4次諧波133與該1.5ω信號以達成5.5ω輸出132之一非臨界相位匹配BBO或氟硼鈹酸鉀(KBBF)晶體。
圖2A圖解說明一例示性五次諧波產生器模組250。在此實施例中，一二次諧波產生器201自該五次諧波產生器模組250外部之一級接收一基諧波200(ω)(或一未耗盡基諧波)且使該基諧波200加倍以產生一2次諧波202。一四次諧波產生器204接收2次諧波202並使該2次諧波202加倍以產生一4次諧波205。一五次諧波產生器207組合4次諧波205與來自二次諧波產生器201之一未耗盡基諧波203以產生一5次諧波輸出210。注意，四次諧波產生器204之一未耗盡2次諧波206、五次諧波產生器207之一未耗盡基諧波208及五次諧波產生器207之一未耗盡4次諧波209未用於此實施例中，且因此可與輸出分離(若需要)。在一實施例中，可如圖1A中之虛線104’所示般將未耗盡基諧波208重定向至該圖之OP模組103。
圖2B圖解說明另一例示性五次諧波產生器模組260。在此實施例中，一二次諧波產生器211自該五次諧波產生器模組外部之一級接收一基諧波222(ω)(或一未耗盡基諧波)且使該基諧波222加倍以產生一2次諧波212。一三次諧波產生器214組合2次諧波212以及二次諧波產生器211之一未耗盡基諧波213以產生一3次諧波215。一五次諧波產生器218組合3次諧波215與3次諧波產生器214之一未耗盡2次諧波216以產生一5次諧波輸出219。注意三次諧波產生器214之一未耗盡基諧波217、五次諧波產生器218之一未耗盡2次諧波220及五次諧波產生器218之一未耗盡3次諧波221未用於此實施例中，且因此可與輸出分離(若需要)。注意在一實施例中，可如圖1A中之虛線104’所示般將未耗盡基諧波217引導至該圖之OP模組103。
圖3A圖解說明又另一例示性五次諧波產生器模組300。在此實施例中，一四次諧波產生器302自該五次諧波產生器模組300外部之一級接收一2次諧波301且使該2次諧波301加倍以產生一4次諧波303。一五次諧波產生器305組合4次諧波303以及來自該五次諧波產生器模組300外部之一級之一基諧波308(或一未耗盡基諧波)以產生一5次諧波輸出308。注意，4次諧波產生器302之一未耗盡2次諧波304、五次諧波產生器305之一未耗盡基諧波306及五次諧波產生器305之一未耗盡4次諧波307未用於此實施例中，且因此可與輸出分離(若需要)。注意在一實施例中，可如圖1B中之虛線115’所示般將未耗盡2次諧波304引導至該圖之OP模組114。
圖3B圖解說明又另一例示性五次諧波產生器模組310。在此實施例中，一三次諧波產生器313組合來自該五次諧波產生器模組310外部之一級之一基諧波311(或一未耗盡基諧波)與亦來自該五次諧波產生器模組310外部之一級之一2次諧波312(或一未耗盡2次諧波)以產生一3次諧波315。一五次諧波產生器317組合3次諧波315與來自3次諧波產生器313之一未耗盡2次諧波以產生一5次諧波輸出320。注意3次諧波產生器313之一未耗盡基諧波314、5次諧波產生器317之一未耗盡2次諧波318及五次諧波產生器317之一未耗盡3次諧波319未用於此實施例中，且因此可與輸出分離(若需要)。注意在一實施例中，未耗盡二次諧波318可如圖1B中之虛線115’所示般引導至該圖之OP模組114。
圖4圖解說明用於產生大約193.4奈米之一UV波長之另一例示性雷射系統400。在此實施例中，在一頻率ω下操作之一基諧波雷射401產生一基諧波402。一OP模組403使用基諧波402以產生一簡併或非簡併輸出頻率405。因此，例如，若該基諧波402的波長為1063.5奈米，則輸出頻率之經降頻轉換的光波長係2127奈米，其係兩倍於基諧波402的波長。在另一實例中，若基諧波402的波長為1064.4奈米且所要輸出波長係193.368奈米，則該輸出頻率405將對應於2109.7奈米之信號波長。在一些實施例中，OP模組403可包含一非線性晶體，諸如週期極化鈮酸鋰、掺雜氧化鎂之鈮酸鋰或KTP。在一些實施例中，OP模組403可包含一低功率雷射，諸如二極體雷射或一低功率光纖雷射。
一二次諧波產生器406使來自OP模組403之一未耗盡基諧波404加倍以產生一2次諧波407。一四次諧波產生器409使2次諧波407加倍以產生一4次諧波410。一混頻模組412組合該輸出頻率405與該4次諧波410以產生一大約4.5次諧波413，其具有大約236奈米之一波長。一混頻模組416混合該大約4.5次諧波413及來自二次諧波產生器406之一未耗盡基諧波408以產生具有大約193.368奈米之一波長之一大約5.5ω雷射輸出417。
注意四次諧波產生器409之一未耗盡2次諧波411、來自混頻模組412之一未耗盡4次諧波及未耗盡OP信號414未用於此實施例中，且因此可與輸出分離(若需要)。
進一步需注意，基諧波(ω)係用於三個模組中：二次諧波產生器406、混頻模組416及OP模組403。用於充分利用來自一產生器或模組之未耗盡基諧波之各種不同的方案係可行的。例如，在一些實施例中，該基諧波可包含來自二次諧波產生器406之一未耗盡基諧波404’而非如基諧波402所示般藉由基諧波雷射401直接提供至OP模組403。同樣地，在某些較佳實施例中，基諧波(ω)402’可直接提供至二次諧波產生器406以便更容易地產生更多二次諧波407。可將來自二次諧波產生器406之輸出之未耗盡基諧波408及/或404’分別引導至混頻模組416及/或OP模組403。在一些實施例中，可將來自混頻模組416之一未耗盡基諧波418’引導至OP模組403。
應瞭解，各種雷射系統之圖式旨在圖解說明例示性組件/步驟以由一預定頻率輸入光產生一預定頻率輸出光。為簡單起見，該等圖式展示此程序中涉及的主要光學模組及諧波產生器。因此，該等圖式並非意欲表示該等組件之實際實體佈局，且實際實施方案通常將包含額外的光學元件。
例如，在本文所述之任一實施例中，可視需要使用鏡以引導基諧波或其他諧波。例如，可視需要使用諸如稜鏡、光束分割器、光束組合器及二向色塗佈鏡之其他光學組件以分離並組合光束。可使用鏡及光束分割器之各種組合以依任何適當序列分離並路由不同諧波產生器與混頻器之間的各種波長。可適當地使用透鏡及/或曲面鏡以將光束腰聚焦至非線性晶體內部或附近的實質上圓形或橢圓形截面之焦點。可視需要使用稜鏡、光柵或繞射光學元件以分離諧波產生器及混頻器模組之輸出處的不同波長。可視情況使用稜鏡、塗佈鏡或其他元件以組合諧波產生器及混頻器之輸入處的不同波長。可視情況使用光束分割器或塗層鏡以分離波長或將一波長分為兩個光束。可使用濾光器以在任何級之輸出處阻斷非所要及/或未耗盡波長。例如，可視需要使用波板以旋轉偏光以便相對於一非線性晶體之軸準確地對準一輸入波長之偏光。自該等圖式及其等相關聯描述，熟習此項技術者將瞭解如何構建根據實施例之雷射。
雖然在實施例中未耗盡基諧波及未耗盡諧波(當一後續諧波產生器不需要時)係展示為與所要諧波分離，但是在一些情況中即使一後續諧波產生器中無需未耗盡光，容許該光通過至該諧波產生器亦係可接受的。若功率密度足夠低而不損壞該級之組件且若存在所要頻率轉換程序之最小干擾(例如，由於未使用在晶體角度之相位匹配)，則未耗盡光之此傳送係可接受的。熟習此項技術者將瞭解各種權衡及替代物以判定未耗盡基諧波/諧波是否應與所要諧波分離。
在一實施例中，上述二次諧波產生器之至少一者可包含一LBO晶體，其在約149°C之溫度下實質上非臨界地相位匹配以產生大約532奈米的光。在一實施例中，上述三次諧波產生器之至少一者可包含CLBO、BBO、LBO或其他非線性晶體。在一實施例中，上述四次諧波產生器及五次諧波產生器之至少一者可使用CLBO、BBO、LBO或其他非線性晶體中之臨界相位匹配。在一些實施例中，混合5ω與大約0.5ω之混頻模組(諸如圖1A中的108及圖1B中的118)可包含一CLBO或一LBO晶體，其係與一高Deff
(~1 pm/V)及一低走離角(對於CLBO＜45毫弧度且對於LBO＜10毫弧度)臨界地相位匹配。在其他實施例中，諸如圖1C中混合4ω與大約1.5ω之混頻模組131或圖4中混合大約4.5ω與基諧波之混頻模組416可包含一BBO或KBBF晶體。
在一些實施例中，四次諧波產生器、五次諧波產生器及/或混頻模組可有利地使用以下申請案中揭示之一些或所有方法及系統：於2012年3月5日申請之標題為「Laser with high quality, stable output beam, and long-life high-conversion-efficiency non-linear crystal」之美國專利申請案13/412,564以及於2011年7月22日申請之標題為「Mode-locked UV laser with high quality, stable output beam, long-life high conversion efficiency non-linear crystal and a wafer inspection system using a mode-locked laser」之美國臨時申請案第61/510,633號(且美國專利申請案13/412,564主張其優先權)，該等案皆以引用方式併入本文。
在一些實施例中，本文論述之任何諧波產生器可有利地包含氫退火非線性晶體。此等晶體可如以下申請案中所述般進行處理：於2012年6月1日申請之Chuang等人之標題為「Hydrogen Passivation of Nonlinear Optical Crystals」之美國專利申請案13/488,635及於2011年10月7日申請之Chuang等人之標題為「Improvement of NLO Crystal Properties by Hydrogen Passivation」之美國臨時申請案61/544,425。此等申請案皆係以引用方式併入本文。氫退火晶體在涉及深UV波長之該等級(例如，四次諧波產生器及五次諧波產生器以及混頻模組)中可尤其有用。
注意在一些實施例中，在OP模組內部放置混合OP模組之信號頻率或閒頻信號頻率與四次諧波或五次諧波之混頻模組。此避免需要將該信號頻率或閒頻信號頻率帶出該OP模組。其亦具有以下優點：使最高信號或閒頻信號(視情況)功率位準可用於混頻，從而使混合更有效率。
在一實施例中，為在基諧波(例如，大約1063.5奈米波長)下產生足夠功率，可使用一或多個放大器以增加該基諧波之功率。若使用兩個或更多個放大器，則可使用一種子雷射以接種該等放大器，藉此確保所有放大器輸出相同波長且具有同步輸出脈衝。例如，圖5圖解說明包含產生所要基諧波長(例如，大約1063.5奈米)之種子光之一種子雷射(穩定化窄頻雷射)503之一基諧波雷射500之一例示性組態。種子雷射503可藉由(例如)一摻釹YAG雷射、一摻釹釩酸釔雷射、一光纖雷射或一穩定化二極體雷射實施。
放大器502將種子光放大至一較高功率位準。在一實施例中，放大器502可包含摻釹YAG、摻釹釩酸釔或釩酸釓與釩酸釔之摻釹混合物。在其他實施例中，放大器502可包含摻鐿光纖放大器。一放大器泵浦501可用以泵激放大器502。在一實施例中，放大器泵浦501可包含在大約808奈米波長下操作之一或多個二極體雷射。
因為多個頻率轉換級可需要基諧波雷射波長(取決於近似193.4奈米波長所需之輸出功率)，所以需要的基諧波雷射光多於可藉由一單個放大器方便地產生之光。在此等情況中，可使用多個放大器。例如，在基諧波雷射500中，除放大器502及放大器泵浦501以外亦可提供一放大器506及一放大器泵浦507。如同放大器502，放大器506亦可將種子光放大至一較高功率。放大器泵浦507可泵激放大器506。
在一多個放大器實施例中，各放大器可產生其本身的基諧波雷射輸出。在圖5中，放大器502可產生基諧波雷射輸出(基諧波)508且放大器506可產生基諧波雷射輸出(基諧波)509。在此組態中，基諧波508及509可被引導至不同的頻率轉換級。注意，為確保基諧波508及509的波長相同且同步，種子雷射503應對放大器502及506提供相同的種子光，放大器502與506應實質上相同且放大器泵浦501與507應實質上相同。為確保對放大器502及506二者提供相同的種子光，一光束分割器504及一鏡505可***該種子光且將其之一分率引導至放大器506。雖然圖5中僅展示兩個放大器，但是一基諧波雷射之其他實施例可以一類似組態包含更多放大器、放大器泵浦、光束分割器及鏡以產生多個基諧波輸出。
圖6圖解說明產生兩倍於基諧波長(即，基諧波頻率的一半)之紅外光606之一例示性簡併OPA 600。在此實施例中，一光束組合器602組合一基諧波603(例如，1063.5奈米)與由一種子雷射601產生之種子光。在一實施例中，光束組合器602可包含有效地反射一波長同時透射另一波長之二向色塗層。在另一實施例中，光束組合器602可為有效地組合兩個實質上正交偏光之一偏光光束組合器。在圖6中所示之組態中，該兩個波長可實質上共線前進穿過一非線性轉換器604。非線性轉換器604可包括週期極化鈮酸鋰、掺雜氧化鎂之鈮酸鋰、KTP、或其他合適的非線性結晶材料。
在一實施例中，種子雷射601可為一低功率雷射(例如，二極體雷射或低功率光纖雷射)，其產生兩倍於基諧波雷射之波長之一種子波長(例如，若該基諧波雷射係1063.5奈米，則種子波長係2127奈米)。此波長可用以在OPA 600中接種降頻轉換程序。一雷射二極體可基於諸如GaInAs、InAsP或GaInAsSb之一化合物半導體，其中適當的組合物使該化合物半導體之能帶隙匹配於一2127奈米光子之大約0.5829電子伏特能量。在此二極體組態中，種子雷射601的功率僅需要為大約1毫瓦、幾毫瓦或幾十毫瓦。在一實施例中，種子雷射601可藉由使用(例如)一光柵及穩定化溫度而穩定化。種子雷射601可產生偏光，該偏光被引入至(非線性轉換器604之)一非線性晶體中且經偏光實質上垂直於基諧波之偏光。在另一實施例中，(非線性轉換器604之)非線性晶體可包含於一諧振腔中以基於自發發射產生一雷射/放大器。在一實施例中，輸出波長606可使用一光束分割器或稜鏡605而與一未耗盡基諧波607分離。
使用用於簡併降頻轉換之一OPA之一優點係：使用一窄頻穩定化種子雷射信號接種OPA將會導致透過激發發射之一窄頻輸出。此克服簡併降頻轉換產生一寬頻輸出(取決於非線性晶體)之自然傾向，這係因為可在任何波長範圍內自發地產生相位匹配於非線性晶體中之信號及閒頻信號。在一OPO中，通常難以製造在所關注波長之窄頻(通常係本文揭示之雷射系統中之零點幾奈米之一頻寬)中具有高反射率(或視情況透射率)但在該窄頻外部具有極低反射率(或透射率)之濾光器。
一OPA之其他實施例可使用一光子晶體光纖以產生實質上兩倍於基諧波之波長之一波長。一OPA之又其他實施例可使用在大約2127奈米下操作之一種子雷射二極體以接種(非線性轉換器604之)光子晶體光纖降頻轉換器。對降頻轉換使用一非線性光學晶體可能更加有效，這係因為(非線性轉換器604之)非線性晶體係一χ(2)
程序而非一χ(3)
程序。然而，一光子晶體可用於一些境況中。
注意，一雷射可開始於並非確切地等於輸出波長之5.5倍之一波長。例如，基諧波之一波長可為約1064.4奈米，而所要輸出波長接近193.368奈米。在該情況中，可藉由一OPO或OPA產生兩個不同的輸出波長(即，信號及閒頻信號)，而非使用簡併降頻轉換。因為此兩個波長緊靠在一起(例如，在一些實施例中分離幾奈米或幾十奈米)，所以可使用類型II頻率轉換(若可達成相位匹配)，使得信號及閒頻信號具有垂直偏光且可藉由一偏光光束分割器分離。在其他實施例中，可使用適當長度之一標準量具(或適當設計之體積式布拉格光柵)以反射或透射所要波長同時(視情況)不反射或透射另一波長。
圖7圖解說明產生稍微自兩倍基諧波長(即，基諧波頻率的一半)移位之紅外光706之一例示性非簡併OPA 700。在此實施例中，一光束組合器702組合一基諧波703(例如，1064.4奈米)與由一種子雷射701產生之種子光(若基諧波為1064.4奈米且所要雷射系統輸出波長係193.368奈米，則種子光波長為(例如)2109.7奈米)。此基諧波長可藉由一摻釹YAG雷射、一摻釹釩酸釔雷射、釩酸釓與釩酸釔之一摻釹混合物雷射或一摻鐿光纖雷射產生。在一實施例中，光束組合器702可包含有效地反射一波長同時有效地透射另一波長之一二向色塗層或一繞射光學元件。在此組態中，該兩個波長可實質上共線前進穿過一非線性轉換器704。非線性轉換器704可包括週期極化鈮酸鋰、掺雜氧化鎂之鈮酸鋰、KTP或其他合適的非線性結晶材料。非線性轉換器704可放大種子波長且亦產生一第二波長(若基諧波長係1064.4奈米且種子波長係2109.7奈米，則該第二波長將約等於2148.2奈米)。
可使用諸如一輸出光束分割器、濾波器、標準量具或繞射光學元件之一元件705以使一非所要(例如，大約2148.2奈米)波長707與所要(大約2109.7奈米)波長706分離。若需要，元件705亦可用以使任何未耗盡基諧波與輸出光束706分離。在一些實施例中，可接種一閒頻信號波長(諸如2148.2奈米)而非信號波長。注意當接種閒頻信號時，藉由基諧波雷射及種子雷射二者之頻寬判定信號頻寬，而當接種信號時，在很大程度上藉由種子雷射頻寬判定信號之頻寬。
在分離此兩個波長之後，信號頻率(例如，波長係2109.7奈米)可與基諧波之五次諧波(例如，其之一波長係實質上212.880奈米)混合以產生實質上193.368奈米之一輸出波長。可在上述任一實施例或其等效物之後完成此混合。或者，該實質上2109.7奈米波長可與基諧波之四次諧波(其之一波長係實質上266.1奈米)混合以產生實質上236.296奈米之光。此繼而可與基諧波(或一未耗盡基諧波)混合以產生實質上193.368奈米之一輸出波長。可在圖4中所示之實施例或其等效物之任一者之後完成此混合。
對於基諧波雷射，可使用一高重複率雷射(諸如在大約50兆赫茲或較高重複率下操作之一鎖模雷射)建構一準CW雷射操作。對於基諧波雷射，可使用一CW雷射建構一真實的CW雷射。一CW雷射可需要包含於諧振腔中之頻率轉換級之一或多者以增建足以得到有效頻率轉換之功率密度。
圖8至圖15圖解說明可包含使用OP模組進行頻率轉換之上述雷射系統之系統。此等系統可用於光罩、倍縮光罩或晶圓檢測應用中。
圖8圖解說明用於檢測一基板812之表面之一例示性光學檢測系統800。系統800大體上包含一第一光學配置851及一第二光學配置857。如所示，第一光學配置851包含至少一光源852、檢測光學器件854及參考光學器件856，而該第二光學配置857包含至少透射光光學器件858、透射光偵測器860、反射光光學器件862及反射光偵測器864。在一較佳組態中，光源852包含上述改良之雷射之一者。
光源852經組態以發射行進穿過一聲光裝置870之一光束，該聲光裝置870經配置以使該光束偏轉並聚焦。聲光裝置870可包含一對聲光元件(例如，一聲光預掃描儀及一聲光掃描儀)，其等使光束在Y方向上偏轉且將其聚焦在Z方向上。例如，多數聲光裝置藉由發送一RF信號至石英或一晶體(諸如TeO2
)而操作。此RF信號導致一聲波前進穿過該晶體。由於正在前進的聲波，該晶體變得不對稱，從而導致折射率貫穿該晶體而改變。此改變導致入射光束形成以一振盪方式偏轉之一聚焦前進光點。
當光束自聲光裝置870出射時，該光束接著行進穿過一對四分之一波板872及一中繼透鏡874。中繼透鏡874經配置以準直光束。接著，經準直光束繼續在其路徑上直至其到達一繞射光柵876。繞射光柵876經配置以展開(flare out)該光束且更特定言之將該光束分離為三個相異光束，該等光束在空間上可彼此區分(即，空間相異)。在多數情況中，該等空間相異光束亦經配置以等距隔開且具有實質上相等的光強度。
在該三個光束離開該繞射光柵876之後，其等行進穿過一孔徑880且接著繼續直至其等到達一光束分割器立方體882。光束分割器立方體882(結合四分之一波板872)經配置以將該等光束***為兩個路徑，即一路徑向下引導且另一路徑引導至右側(在圖8中所示之組態中)。向下引導之路徑係用以將該等光束之一第一光部分配至基板812，而引導至右側之路徑係用以將該等光束之一第二光部分分配至參考光學器件856。在多數實施例中，將大部分光分配至基板812且將較小百分比之光分配至參考光學器件856，但是百分比比率可根據各光學檢測系統之特定設計而改變。在一實施例中，參考光學器件856可包含一參考集光透鏡814及一參考偵測器816。參考集光透鏡814經配置以收集光束之部分並將光束之部分引導於參考偵測器816上，該參考偵測器經配置以量測光強度。參考光學器件通常在此項技術中為人所熟知且為簡單起見將不會加以詳細論述。
自光束分割器882向下引導之三個光束係由一望遠鏡888接收，該望遠鏡888包含重定向並擴張光之若干透鏡元件。在一實施例中，望遠鏡888係包含圍繞一轉座旋轉之複數個望遠鏡之一望遠鏡系統之部分。例如，可使用三個望遠鏡。此等望遠鏡之目的係改變基板上之掃描光點的大小且藉此容許選擇最小可偵測缺陷大小。更特定言之，該等望遠鏡之各者大體上表示一不同像素大小。因而，一望遠鏡可產生一較大光點大小，從而使檢測更快且更不敏度(例如，低解析度)，而另一望遠鏡可產生一較小光點大小，從而使檢測更慢且更敏度(例如，高解析度)。
從望遠鏡888觀看，該三個光束行進穿過經配置以將該等光束聚焦至基板812之表面上之一物鏡890。在該等光束與表面交叉為三個相異光點時，可產生反射光束及透射光束二者。該等透射光束行進穿過基板812，而該等反射光束自表面反射。例如，該等反射光束可自該基板之不透明表面反射，且該等透射光束可透射穿過該基板之透明區。該等透射光束係藉由透射光光學器件858收集且該等反射光束係藉由反射光光學器件862收集。
關於透射光光學器件858，該等透射光束在行進穿過基板812之後係藉由一第一透射透鏡896收集且在一球面像差校正器透鏡898的幫助下聚焦至一透射稜鏡810上。稜鏡810可經組態以具有針對該等透射光束之各者之一琢面，琢面經配置以重定位且折曲該等透射光束。在多數情況中，稜鏡810係用以分離該等光束使得其等各自落在透射光偵測器配置860(展示為具有三個相異偵測器)中之一單個偵測器上。因此，當該等光束離開稜鏡810之後，其等行進穿過一第二透射透鏡802，該第二透射透鏡802將分離光束之各者個別地聚焦至該三個偵測器之一者上，該三個偵測器之各者經配置以量測透射光之強度。
關於反射光光學器件862，反射光束在自基板812反射之後係藉由物鏡890收集，該物鏡890接著引導該等光束朝向望遠鏡888。在到達望遠鏡888之前，該等光束亦行進穿過一四分之一波板804。一般而言，物鏡890及望遠鏡888以在光學上相對於如何操縱入射光束逆轉之一方式操縱收集光束。即，物鏡890重新準直該等光束，且望遠鏡888減小其等大小。當該等光束離開望遠鏡888時，其等繼續(向後)直至其等到達光束分割器立方體882。光束分割器882經組態以與四分之一波板804一起運作以將該等光束引導至一中心路徑806上。
接著，藉由一第一反射透鏡808收集繼續在路徑806上之光束，該第一反射透鏡808將該等光束之各者聚焦至一反射稜鏡809上，該反射稜鏡809包含針對該等反射光束之各者之一琢面。反射稜鏡809經配置以重定位且折曲該等反射光束。類似於透射稜鏡810，反射稜鏡809係用以分離該等光束使得其等各自落在反射光偵測器配置864中之一單個偵測器上。如所示，反射光偵測器配置864包含三個個別相異偵測器。當該等光束離開反射稜鏡809時，其等行進穿過一第二反射透鏡811，該第二反射透鏡811將分離光束之各者個別地聚焦至此等偵測器之一者上，此等偵測器之各者經配置以量測反射光之強度。
存在可藉由前述光學總成促進之多個檢測模式。例如，光學總成可促進一透射光檢測模式、一反射光檢測模式及一同時檢測模式。關於透射光檢測模式，透射模式偵測通常用於基板(諸如具有透明區及不透明區之習知光學遮罩)上之缺陷偵測。在光束掃描該遮罩(或基板812)時，光在透明點穿透該遮罩且藉由透射光偵測器860偵測，該等透射光偵測器860定位於該遮罩後面且量測藉由包含第一透射透鏡896、第二透射透鏡802、球面像差透鏡898及稜鏡810之透射光光學器件858收集之光束之各者的強度。
關於反射光檢測模式，可對含有呈鉻、顯影光阻劑及其他特徵之形式之影像資訊之透明或不透明基板執行反射光檢測。藉由基板812反射的光沿與檢測光學器件854相同之光學路徑向後行進，但是接著藉由一偏光光束分割器882轉向至偵測器864中。更特定言之，第一反射透鏡808、稜鏡809及第二反射透鏡811將來自經轉向光束之光投影至偵測器864上。反射光檢測亦可用以偵測不透明基板表面之頂部上的污染。
關於同時檢測模式，利用透射光及反射光二者以判定一缺陷之存在及/或類型。系統之兩個量測值係透射穿過基板812如藉由透射光偵測器860感測之光束之強度及如藉由反射光偵測器864偵測之反射光束之強度。接著，可處理該等兩個量測值以判定基板812上之一對應點處之缺陷(若有)之類型。
更特定言之，同時透射及反射偵測可揭示藉由透射偵測器感測之一不透明缺陷的存在，而反射偵測器之輸出可用以揭示缺陷類型。作為一實例，一基板上之一鉻點或一粒子皆可導致來自透射偵測器之一低透射光指示，但是一反射鉻缺陷可導致來自反射光偵測器之一高反射光指示且一粒子可導致來自相同反射光偵測器之一較低反射光指示。因此，藉由使用反射及透射偵測二者，可定位鉻幾何結構的頂部上之一粒子，若僅檢查缺陷之反射特性或透射特性，則不能進行此定位。此外，可判定某些類型缺陷的訊符，諸如其等反射光強度與透射光強度之比率。接著，可使用此資訊以對缺陷自動分類。於1996年10月8日發佈且以引用方式併入本文之美國專利5,563,702描述關於系統800之額外細節。
根據本發明之某些實施例，併有一大約193奈米雷射系統之一檢測系統可同時偵測一單個偵測器上之兩個資料通道。此一檢測系統可用以檢測諸如一倍縮光罩、一光罩或一晶圓之一基板，且可如由Brown等人於2009年5月5日發佈且以引用方式併入本文之美國專利7,528,943中所述般進行操作。
圖9展示同時偵測一感測器970上之兩個影像或信號通道之一倍縮光罩、光罩或晶圓檢測系統900。照明源909併有如本文所述之一193奈米雷射系統。光源可進一步包括一脈衝倍增器及/或一相干性減小方案。當一受檢測物體930係透明(例如一倍縮光罩或光罩)時，該兩個通道可包括反射強度及透射強度，或可包括兩個不同的照明模式，諸如入射角、偏光狀態、波長範圍或其等之某個組合。
如圖9中所示，照明中繼光學器件915及920將來自源909之照明中繼至該受檢測物體930。該受檢測物體930可為一倍縮光罩、一光罩、一半導體晶圓或待檢測之其他物品。影像中繼光學器件955及960將藉由該受檢測物體930反射及/或透射之光中繼至感測器970。對應於該兩個通道之偵測信號或影像之資料係展示為資料980且傳輸至一電腦(未展示)以供處理。
圖10圖解說明包含多個物鏡及上述改良之雷射之一者之一例示性檢測系統1000。在系統1000中，將來自一雷射源1001之照明發送至照明子系統之多個區段。照明子系統之一第一區段包含元件1002a至1006a。透鏡1002a聚焦來自雷射1001之光。來自透鏡1002a之光接著自鏡1003a反射。為圖解之目的，鏡1003a放置在此位置處且可定位在別處。來自鏡1003a之光接著藉由形成照明光瞳平面1005a之透鏡1004a收集。可取決於檢測模式之要求而在光瞳平面1005a中放置一孔徑、濾波器或用以修改光之其他裝置。來自光瞳平面1005a之光接著行進穿過透鏡1006a且形成照明場平面1007。
照明子系統之一第二區段包含元件1002b至1006b。透鏡1002b聚焦來自雷射1001之光。來自透鏡1002b之光接著自鏡1003b反射。來自鏡1003b之光接著藉由形成照明光瞳平面1005b之透鏡1004b收集。可取決於檢測模式之要求而在光瞳平面1005b中放置一孔徑、濾波器或用以修改光之其他裝置。來自光瞳平面1005b之光接著行進穿過透鏡1006b且形成照明場平面1007。來自該第二區段之光接著藉由鏡或反射表面重定向使得照明場平面1007處之照明場光能包括經組合照明區段。
場平面光接著在自一光束分割器1010反射之前藉由透鏡1009收集。透鏡1006a及1009在物鏡光瞳平面1011處形成第一照明光瞳平面1005a之一影像。同樣地，透鏡1006b及1009在物鏡光瞳平面1011處形成第二照明光瞳平面1005b之一影像。一物鏡1012(或替代地1013)接著獲取光瞳光且在樣本1014處形成照明場1007之一影像。物鏡1012或物鏡1013可定位成接近於樣本1014。樣本1014可在一載物台上移動(未展示)，從而將該樣本定位在所要位置中。自該樣本1014反射及散射之光係藉由高NA折反射物鏡1012或物鏡1013收集。在物鏡光瞳平面1011處形成一反射光光瞳之後，光能在成像子系統中形成一內場1016之前通過光束分割器1010及透鏡1015。此內部成像場係樣本1014及對應照明場1007之一影像。此場可在空間上分離為對應於照明場之多個場。此等場之各者可支援一單獨成像模式。
可使用鏡1017重定向此等場之一者。重定向光接著在形成另一成像光瞳1019b之前行進穿過透鏡1018b。此成像光瞳係光瞳1011及對應照明光瞳1005b之一影像。可取決於檢測模式之要求而在光瞳平面1019b中放置一孔徑、濾波器或用以修改光之其他裝置。來自光瞳平面1019b之光接著行進穿過透鏡1020b且在感測器1021b上形成一影像。以一類似方式，經過鏡或反射表面1017之光係藉由透鏡1018a收集且形成成像光瞳1019a。來自成像光瞳1019a之光接著在偵測器1021a上形成一影像之前藉由透鏡1020a收集。成像於偵測器1021a上之光可用於不同於成像於感測器1021b上之光之一成像模式。
系統1000中所採用之照明子系統係由雷射源1001、集光光學器件1002至1004、放置成接近於一光瞳平面1005之光束塑形組件及中繼光學器件1006及1009組成。一內場平面1007定位在透鏡1006與1009之間。在一較佳組態中，雷射源1001可包含上述改良之雷射之一者。
關於雷射源1001，雖然圖解說明為具有兩個透射點或角度之一單個均勻區塊，但是實際上此表示能夠提供兩個照明通道(例如一第一光能通道(諸如在一第一頻率下行進穿過元件1002a至1006a之雷射光能)及一第二光能通道(諸如在一第二頻率下行進穿過元件1002b至1006b之雷射光能))之一雷射源。可採用不同的光能模式，諸如在一通道中採用明場模式且在另一通道中採用一暗場。
雖然來自雷射源1001之光能經展示以90度間隔發射且該等元件1002a至1006a及1002b至1006b係定向成90度角，但是實際上可以各種定向(不一定係二維)發射光且該等組件可不同於所示般進行定向。因此，圖10僅係所採用的組件之一表示且所示的角度或距離並未按比例繪製亦非設計特定要求。
可在使用孔徑塑形之概念之當前系統中採用放置成接近於光瞳平面1005之元件。使用此設計，可實現均勻照明或近似均勻照明以及個別點照明、環狀照明、四極照明或其他所要圖案。
可在一般的成像子系統中採用物鏡之各種實施方案。可使用一單個固定物鏡。該單個物鏡可支援所有所要成像及檢測模式。若成像系統支援一相對較大的場大小及相對較高的數值孔徑，則可達成此一設計。可藉由使用放置在光瞳平面1005a、1005b、1019a及1019b處之內部孔徑將數值孔徑減小至一所要值。
亦可如圖10中所示般使用多個物鏡。例如，雖然展示兩個物鏡1012及1013，但是任何數目個物鏡係可行的。可針對藉由雷射源1001產生之各波長最佳化此一設計中之各物鏡。此等物鏡1012及1013可具有固定位置或移動至接近於該樣本1014之位置中。為使多個物鏡移動而接近於該樣本，可如標準顯微鏡上所常見般使用旋轉轉座。可使用用於在一樣本附近移動物鏡之其他設計，該等設計包含(但不限於)在一置物台上橫向平移該等物鏡及使用一測向器在一弧上平移該等物鏡。此外，可根據本系統達成固定物鏡與一轉座上之多個物鏡之任何組合。
此組態之最大數值孔徑可接近或超過0.97，但是在某些例項中可更高。此高NA折反射成像系統可能具有之大範圍的照明及收集角結合其大的場大小容許該系統同時支援多個檢測模式。如可從先前段落所了解，可使用一單個光學系統或搭配照明裝置之機器實施多個成像模式。針對照明及收集揭示之高NA允許使用相同的光學系統實施成像模式，藉此容許針對不同類型的缺陷或樣本最佳化成像。
成像子系統亦包含中間影像形成光學器件1015。該影像形成光學器件1015之目的係形成樣本1014之一內部影像1016。在此內部影像1016處，可放置一鏡1017以重定向對應於該等檢測模式之一者之光。可重定向此位置處之光，這係因為用於成像模式之光在空間上分離。可以若干不同形式(包含可變焦距變焦(varifocal zoom)、具有聚焦光學器件之多個無焦管透鏡或多個影像形成mag管)實施影像形成光學器件1018(1018a及1018b)及1020(1020a及1020b)。於2009年7月16日發表且以引用方式併入本文之美國公開申請案2009/0180176描述關於系統1000之額外細節。
圖11圖解說明包含三個子區段1101A、1101B及1101C之一例示性超寬頻UV顯微鏡成像系統1100。子區段1101C包含一折反射物鏡區段1102及一變焦管透鏡1103。折反射物鏡區段1102包含一折反射透鏡群組1104、一場透鏡群組1105及一聚焦透鏡群組1106。系統1100可將一物體/樣本1109(例如，正檢測之一晶圓)成像至一影像平面1112。
折反射透鏡群組1104包含一近似平面(或平面)反射體(其係一反射性塗佈透鏡元件)、一凹凸透鏡(其係一折射表面)及一凹球面反射體。該兩個反射元件可具有不具備反射材料之中心光學孔徑以容許來自一中間影像之光行進穿過該凹球面反射體、藉由該近似平面(或平面)反射體反射至該凹球面反射體上，且往回行進穿過該近似平面(或平面)反射體，從而橫越途中之相關聯透鏡元件或若干相關聯透鏡元件。折反射透鏡群組1104經定位以形成中間影像之一實像，使得結合變焦管透鏡1103在波長帶內實質上校正系統之初級縱向色彩。
場透鏡群組1105可由兩種或更多種不同的折射材料(諸如熔融矽及氟化玻璃)或繞射表面製成。場透鏡群組1105可光學地耦合在一起或替代地可在空氣中稍微隔開。因為熔融矽及氟化玻璃之色散在深紫外線範圍中並無實質上不同，所以該場透鏡群組之若干組件元件之個別功率必須為高量值以提供不同色散。場透鏡群組1105具有沿接近中間影像之光學路徑對準之一凈正光焦度。使用此一褪色場透鏡容許在一超寬光譜範圍內完全校正包含至少次級縱向色彩以及初級及次級橫向色彩之色像差。在一實施例中，僅一場透鏡組件需具有不同於系統之其他透鏡之一折射材料。
聚焦透鏡群組1106包含較佳全部由單個類型材料形成之多個透鏡元件，其中折射表面具有經選擇以校正單色像差及像差之色變動二者且將光聚焦至一中間影像之曲率及位置。在聚焦透鏡群組1106之一實施例中，具有低功率之透鏡1113之一組合校正球面像差、彗形像差及像散之色變動。一光束分割器1107對一UV光源1108提供一入口。UV光源1108可有利地藉由上述改良之雷射加以實施。
變焦管透鏡1103可全部為相同折射材料(諸如熔融矽)且經設計使得在變焦期間不改變初級縱向色彩及初級橫向色彩。此等初級色像差無須校正為零且在僅使用一玻璃類型之情況下不能校正為零，但是其等必須固定，這係可行的。接著必須修改折反射物鏡區段1102之設計以補償變焦管透鏡1103之此等未經校正但固定的色像差。可變焦或改變放大率而不改變其高階色像差之變焦管透鏡1103包含沿該系統之一光學路徑安置之透鏡表面。
在一較佳實施例中，首先獨立於使用兩種折射材料(諸如熔融矽及氟化鈣)之折反射物鏡1102區段而校正變焦管透鏡1103。接著，組合變焦管透鏡1103與折反射物鏡區段1102，此時可修改折反射物鏡區段1102以補償系統1100之殘餘高階色像差。由於場透鏡群組1105及低功率透鏡群組1113，此補償係可行的。接著，最佳化經組合系統使得改變所有參數以達成最佳效能。
注意，子區段1101A及1101B包含實質上類似於子區段1101C之組件且因此並未加以詳細論述。
系統1100包含一折疊鏡群組1111以提供容許自36X至100X之一變焦之線性變焦運動。大範圍變焦提供連續放大率改變，而精細變焦減小頻疊且容許電子影像處理，諸如針對一重複影像陣列之單元間減法。折疊鏡群組1111可特性化為反射元件之一「長號」系統。變焦係藉由以下動作完成：使變焦管透鏡1103之群組作為一單元而移動且亦移動長號U型滑管之臂。因為長號運動僅影響聚焦且其位置處之f#速度極低，所以此運動之精確度可能極為寬鬆。此長號組態之一優點係：其顯著地縮短該系統。另一優點係：僅存在涉及主動(非平坦)光學元件之一變焦運動。且該長號U型滑管之另一變焦運動對錯誤並不敏感。於1999年12月7日發佈且以引用方式併入本文之美國專利5,999,310進一步詳細地描述系統1100。
圖12圖解說明對一折反射成像系統1200添加一法線入射雷射照明(暗場或明場)。系統1200之照明區塊包含：一雷射1201；調適光學器件1202，其等用以控制所檢測表面上之照明光束大小及輪廓；一孔徑與窗1203，其在一機械外殼1204中；及一稜鏡1205，其用以沿光學軸以法線入射至一樣本1208之表面而重定向該雷射。稜鏡1205亦沿光學路徑將來自樣本1208之表面特徵部之鏡面反射及來自一物鏡1206之光學表面之反射引導至一影像平面1209。可以一折反射物鏡、一聚焦透鏡群組及一變焦管透鏡群組(參見圖11)之一般形式提供用於物鏡1206之透鏡。在一較佳實施例中，雷射1201可藉由上述改良之雷射實施。於2007年1月4日發表且以引用方式併入本文之公開專利申請案2007/0002465進一步詳細地描述系統1200。
圖13A圖解說明用於檢測表面1311之區域一表面檢測設備1300，其包含照明系統1301及集光系統1310。如圖13A中所示，一雷射系統1320引導一光束1302穿過一透鏡1303。在一較佳實施例中，雷射系統1320包含上述改良之雷射、一退火晶體及在低溫標準操作期間維持晶體之退火條件之一外殼。第一光束塑形光學器件可經組態以自雷射接收一光束且將該光束聚焦至該晶體中或附近的一光束腰處之一橢圓形截面。
透鏡1303經定向使得其主平面實質上平行於一樣本表面1311且因此在表面1311上於透鏡1303之焦平面中形成照明線1305。此外，以一非正交入射角將光束1302及聚焦光束1304引導至表面1311。特定言之，可以與一法向方向成約1度與約85度之間之一角度將光束1302及聚焦光束1304引導至表面1311。以此方式，照明光線1305實質上係在聚焦光束1304之入射平面中。
集光系統1310包含用於收集自照明線1305散射之光之透鏡1312及用於將由透鏡1312產生的光聚焦至一裝置(諸如電荷耦合裝置(CCD)1314，包括光敏偵測器之一陣列)上之透鏡1313。在一實施例中，CCD 1314可包含偵測器之一線性陣列。在此等情況中，CCD 1314內之偵測器之線性陣列可定向成平行於照明線1305。在一實施例中，可包含多個集光系統，其中該等集光系統之各者包含類似組件，但定向不同。
例如，圖13B圖解說明用於一表面檢測設備之集光系統1331、1332及1333之一例示性陣列(其中為簡單起見未展示其照明系統，例如，類似於照明系統1301)。集光系統1331中之第一光學器件收集在一第一方向上自樣本1311散射之表面之光。集光系統1332中之第二光學器件收集在一第二方向上自樣本1311之表面散射之光。集光系統1333中之第三光學器件收集在一第三方向上自樣本1311之表面散射之光。注意，第一路徑、第二路徑及第三路徑與樣本1311之該表面成不同的反射角。可使用支撐樣本1311之一平台1312以引起該等光學器件與樣本1311之間的相對運動，使得可掃描樣本1311之整個表面。於2009年4月28日發佈且以引用方式併入本文之美國專利7,525,649進一步詳細描述表面檢測設備1300及其他多個集光系統。
圖14圖解說明可用於檢測一表面1401上之異常之一表面檢測系統1400。在此實施例中，表面1401可藉由包括由上述改良之雷射產生之一雷射光束之一雷射系統1430之一實質上固定照明裝置部分照明。雷射系統1430之輸出可連續行進穿過偏光光學器件1421、一光束擴張器與孔徑1422及光束成形光學器件1423以擴張並聚焦光束。
所得聚焦雷射光束1402接著藉由一光束折疊組件1403及一光束偏轉器1404反射以引導光束1405朝向表面1401以用於照明該表面。在較佳實施例中，光束1405實質上法向或垂直於表面1401，但是在其他實施例中光束1405可與表面1401成一傾斜角。
在一實施例中，光束1405實質上垂直或法向於表面1401且光束偏轉器1404將來自表面1401之光束之鏡面反射反射朝向光束轉向組件1403，藉此用作防止該鏡面反射到達偵測器之一防護罩。該鏡面反射之方向係沿線SR，該線SR法向於樣本之表面1401。在光束1405法向於表面1401之一實施例中，此線SR與照明光束1405之方向一致，其中此共同參考線或方向在本文被稱為檢測系統1400之軸。在光束1405與表面1401成一傾斜角之情況下，鏡面反射之方向SR將不會與光束1405之傳入方向一致；在此例項中，指示表面法線之方向之線SR被稱為檢測系統1400之收集部分之主軸。
由小粒子散射之光係藉由鏡1406收集且經引導朝向孔徑1407及偵測器1408。由大粒子散射之光係藉由透鏡1409收集且經引導朝向孔徑1410及偵測器1411。注意，一些大粒子亦使經收集且引導至偵測器1408之光散射，且類似地，一些小粒子亦使經收集且引導至偵測器1411之光散射，但是此光之強度相對較低於各自偵測器經設計以偵測之散射光強度。在一實施例中，偵測器1411可包含光敏元件之一陣列，其中該光敏元件陣列之各光敏元件經組態以偵測照明線之一放大影像之一對應部分。在一實施例中，檢測系統可經組態以用於偵測未經圖案化晶圓上之缺陷。於2001年8月7日發佈且以引用方式併入本文之美國專利6,271,916進一步詳細描述檢測系統1400。
圖15圖解說明經組態以使用法向及傾斜照明光束兩者來實施異常偵測之一檢測系統1500。在此組態中，包含上述改良之雷射之一雷射系統1530可提供一雷射光束1501。一透鏡1502使該光束1501聚焦穿過一空間濾波器1503且透鏡1504準直該光束且將其遞送至一偏光光束分割器1505。光束分割器1505將一第一偏光分量傳遞至法向照明通道且將一第二偏光分量傳遞至傾斜照明通道，其中該第一分量及該第二分量係正交的。在該法向照明通道1506中，該第一偏光分量係藉由光學器件1507聚焦且藉由鏡1508反射朝向一樣本1509之一表面。藉由樣本1509散射之輻射係藉由一抛物面鏡1510收集且聚焦至一光倍增管1511。
在傾斜照明通道1512中，第二偏光分量係藉由光束分割器1505反射至一鏡1513(其使此光束反射穿過一半波板1514)且藉由光學器件1515聚焦至樣本1509。源自該傾斜通道1512中之傾斜照明光束且藉由樣本1509散射之輻射亦係藉由抛物面鏡1510收集且聚焦至光倍增管1511。注意，光倍增管1511具有一針孔入口。該針孔及照明光點(來自表面1509上之法向及傾斜照明通道)較佳處於該抛物面鏡1510之焦點處。
該抛物面鏡1510將來自樣本1509之散射輻射準直成一準直光束1516。接著，準直光束1516係藉由一物鏡1517聚焦且透過一檢偏鏡1518而至該光倍增管1511。注意，亦可使用具有除抛物面形狀以外之形狀之彎曲鏡表面。一儀器1520可提供光束與樣本1509之間之相對運動使得跨樣本1509之表面掃描光點。2001年3月13日發佈且以引用方式併入本文之美國專利6,201,601進一步詳細描述檢測系統1500。
其他倍縮光罩、光罩或晶圓檢測系統可有利地使用上述改良之雷射。例如，其他系統包含美國專利5,563,702、5,999,310、6,201,601、6,271,916、7,352,457、7,525,649及7,528,943中所述之系統。又進一步系統包含美國公開案2007/0002465及2009/0180176中所述之系統。當用於一檢測系統時，此改良之雷射可有利地與已發表之PCT申請案WO 2010/037106及美國專利申請案13/073,986中所揭示之相干性及斑紋減小設備及方法組合。此改良之雷射亦可有利地與以下申請案中所揭示之方法及系統組合：2011年6月13日申請之標題為「Optical peak power reduction of laser pulses and semiconductor and metrology systems using same」之美國臨時申請案61/496,446及2012年6月1日申請且在2012年12月13日作為美國公開案2012/0314286發表之標題為「Semiconductor Inspection And Metrology System Using Laser Pulse Multiplier」之美國專利申請案13/487,075。此段落中敘述之專利、專利公開案及專利申請案係以引用方式併入本文。
雖然一些上述實施例描述被轉換為大約193.368奈米之一輸出波長之一大約1063.5奈米基諧波長，但是應瞭解，可藉由此途徑使用基諧波長及信號波長之一適當選擇產生193.368奈米之幾奈米內之其他波長。此等雷射及利用此等雷射之系統係在本發明之範疇內。
改良之雷射將明顯比8次諧波雷射便宜且具有較長壽命，藉此與8次諧波雷射相比提供更好的持有成本。注意，在近似1064奈米操作之基諧波雷射在功率及重複率之各種組合中可容易地以合理價格獲得。實際上，改良之雷射整體可使用可容易獲得且相對便宜之組件而建構。因為改良之雷射可為一高重複率鎖模或Q切換雷射，所以與一低重複率雷射相比，改良之雷射可簡化倍縮光罩/光罩/晶圓檢測系統之照明光學器件。
上文描述之本發明之結構及方法之各種實施例僅圖解說明本發明之原理且並不旨在將本發明之範疇限於所述之特定實施例。
例如，可產生自兩倍基諧波長移位大約10奈米、20奈米或幾百奈米之一波長而非產生確切兩倍於該基諧波長之一波長。藉由使用並非確切兩倍於基諧波長之一波長，可產生自除以5.5之基諧波長稍微移位之一輸出波長。例如，使基諧波長除以介於大約5.4與5.6之間之一值，或在一些實施例中，使基諧波長除以介於大約5.49與5.51之間之一值。一些實施例降頻轉換基諧波之二次諧波頻率以產生基諧波頻率之大約一半及基諧波頻率之大約1.5倍之頻率。因此，本發明僅受限於下列申請專利範圍及其等效物。 Related applications
This application claims the priority of "Solid-State 193 nm Laser And An Inspection System Using A Solid-State 193 nm Laser" and applied for the priority of US Provisional Application 61 / 650,349 on May 22, 2012. This case is Incorporated herein by reference.
According to one of the improved laser technologies and laser systems described herein, the fundamental harmonic can be selected from one of approximately 1063.5 nm (e.g., approximately 1063.52 nm or in another example between approximately 1064.0 nm and approximately 1064.6 nm) The wave vacuum wavelength produces an ultraviolet (UV) wavelength of about 193.4 nanometers (e.g., a vacuum wavelength of approximately 193.368 nanometers). Where a wavelength is given indefinitely herein, it is assumed that this wavelength refers to the vacuum wavelength of light.
Each embodiment of the present invention uses at least one frequency in more than one frequency conversion stage. In general, the frequency conversion stage does not completely deplete its input light, which can be advantageously used in the improved laser system described herein. A preferred embodiment of the present invention separates an undepleted portion of at least one input wavelength of one stage and redirects the undepleted portion for use in another stage. Frequency conversion and mixing are non-linear programs. Conversion efficiency increases as the input power level increases. For example, the entire output of the fundamental harmonic laser may be first directed to a stage (such as a second-harmonic generator) to maximize the efficiency of the stage and minimize the length (and therefore cost) of the crystals used for the stage. In this example, the undepleted portion of the fundamental harmonic will be directed to another stage (such as a fifth-order harmonic generator or an optical parameter module) for use in that stage.
One advantage of separating an undepleted input frequency and directing it separately to another stage instead of allowing it to co-propagate with the output of that stage is that the optical path length can be controlled individually for each frequency, thereby ensuring that pulses arrive at the same time. Another advantage is that the coating and optical components can be optimized for individual frequencies rather than damaging the coating and optical components between the needs of the two frequencies. Specifically, the output frequency of the second or fourth harmonic generator will have a vertically polarized light relative to the input frequency. A Brewster window used to allow one frequency to enter with minimal reflection will typically have a high reflectivity for another frequency because the polarized light at that other frequency is wrong for the window.
The preferred embodiment of the present invention uses environmental protection for frequency conversion stages and mixing stages that produce deep UV wavelengths, such as wavelengths shorter than about 350 nanometers. U.S. Patent No. 8,298,335 entitled "Enclosure for controlling the environment of optical crystals" issued to Armstrong on October 30, 2012 and titled "Laser With High Quality, Stable Output" issued by Dribinski et al. On January 24, 2013 "Beam, And Long Life High Conversion Efficiency Non-Linear Crystal" describes suitable environmental protection in US Published Application 2013/0021602, both of which are incorporated herein by reference. In particular, Brewster windows can be used in these environments to allow input and output frequencies to enter or leave. Directing each frequency individually allows different Brewster windows or coatings to be used as needed to minimize losses and stray light within the laser system.
The improved laser technology and laser systems described below use half-harmonics to divide the fundamental harmonic length by 5.5 (ie, multiply the fundamental harmonic frequency by 5.5). Note that dividing a wavelength by N can also be described as multiplying its corresponding frequency by N, where N is any number (whether an integer or a fraction). As used in the diagram, ω is specified as the fundamental harmonic frequency. For example, FIGS. 1A to 1C indicate parenthesized parenthesis light wavelengths (relative to the fundamental harmonic frequency) generated by various components of an exemplary laser system, such as (ω), (0.5ω), (1.5ω), ( 2ω), (4ω), (4.5ω), and (5ω). Note that a similar symbol may be used to indicate one harmonic of the fundamental harmonic frequency, for example, the fifth harmonic is equal to 5ω. The harmonics of 0.5ω, 1.5ω, and 4.5ω can also be called half-harmonics. Note that in some embodiments, a frequency slightly shifted from 0.5ω is used instead of exactly 0.5ω. The frequencies described as about 0.5ω, about 1.5ω, etc. may refer to the exact half-harmonic or slightly shifted frequency depending on the embodiment. For ease of reference in describing the elements of these figures, the number notation (for example, "5th harmonic") refers to the frequency itself, and the word notation (for example, "fifth harmonic") refers to the generation of the Frequency component.
FIG. 1A illustrates an exemplary laser system 100 for generating one of ultraviolet (UV) wavelengths of approximately 193.4 nanometers. In this embodiment, the laser system 100 includes a fundamental harmonic laser 101 that generates light of a fundamental harmonic frequency ω (ie, fundamental harmonic 102). In one embodiment, the fundamental harmonic frequency ω may be a frequency corresponding to one of the infrared wavelengths of approximately 1064 nm. For example, in some preferred embodiments, the fundamental harmonic laser 101 may emit substantially one wavelength of 1063.52 nanometers. In other embodiments, the fundamental harmonic laser 101 may emit a wavelength between about 1064.0 nm and about 1064.6 nm. The fundamental harmonic laser 101 can be implemented by using one of a suitable laser medium such as a neodymium-doped yttrium aluminum garnet (Nd: YAG) or a neodymium-doped yttrium vanadate. A neodymium-doped mixture of praseodymium vanadate and yttrium vanadate (for example, about 50:50 of one of the two vanadates) is another suitable laser medium that can have a high wavelength at a wavelength of approximately 1063.5 nm Gain on Nd: YAG or Nd: YAG. An erbium-doped fiber laser can be used to generate another alternative to laser light with a wavelength of approximately 1063.5 nm. Lasers that can be modified or tuned to operate at approximately 1063.5 nanometers are available as pulsed lasers (Q-switched or mode-locked) or continuous wave (CW) lasers. Exemplary manufacturers of such modifiable lasers include Coherent Inc. (e.g., models in the Paladin family with repetition rates of 80 MHz and 120 MHz), Newport Corporation (e.g., models in Explorer family), and others manufacturer. Techniques that can be used with the fundamental harmonic laser 101 to control wavelength and bandwidth include distributed feedback or use of wavelength selective devices such as fiber Bragg gratings, diffraction gratings or standard gages. In other embodiments, a commercially available laser system such as the one just listed operates at its standard wavelength, which is typically a wavelength between about 1064.0 nm and about 1064.6 nm. In these embodiments, the frequency of the signal or idler signal (see below) can be shifted from exactly 0.5ω to produce the desired output wavelength.
Note that the fundamental harmonic laser 101 determines the overall stability and bandwidth of the output light. At low and medium power levels, such as the level of about 1 milliwatt to tens of watts, it is often easier to achieve stable narrow-bandwidth lasers. Stabilizing wavelengths and reducing the bandwidth of higher power or shorter wavelength lasers is more complex and expensive. The laser power level of the fundamental harmonic laser 101 can be in the range of milliwatts to tens of watts or more. Therefore, the fundamental harmonic laser 101 can be easily stabilized.
The fundamental harmonic 102 may be directed towards an optical parameter oscillator (OPO) or an optical parameter amplifier (OPA). OPO, which oscillates at one optical frequency, down-converts its input frequency to one or two output frequencies through a second-order nonlinear optical interaction. In the case of two output frequencies, a "signal" frequency and a "idle signal" frequency are generated (shown as "signal + idle signal" in the figure). The sum of the two output frequencies is equal to the input frequency. In the case of an output frequency (referred to as a degenerate OP module), the signal frequency is the same as the idle frequency signal and it is therefore difficult to distinguish it for all practical purposes. An OPA is a laser light source that amplifies an input wavelength of seed (or input) light using an optical parameter amplification program. For simplicity, this article uses the general term "OP module" to refer to an OPO or an OPA.
In the laser system 100, an OP module 103 down-converts a part of the fundamental harmonic 102 into a degenerate output frequency (about 0.5ω) 107. Therefore, in the degenerate case, the wavelength of the light output converted by the down conversion of the OP module 103 is twice the wavelength of the fundamental harmonic 102. For example, if the fundamental harmonic 102 has a wavelength of 1063.5 nanometers, the wavelength of the signal 107 is 2127 nanometers. In some embodiments, the OP module 103 may include a non-linear crystal, such as periodically polarized lithium niobate, magnesium oxide-doped lithium niobate, or potassium titanyl phosphate (KTP). In some embodiments, the OP module 103 may include a low-power laser, such as a diode laser or a low-power fiber laser.
Note that only a portion of the fundamental harmonic 102 is depleted in the down-conversion procedure. In fact, in general, OP modules and harmonic generators have not completely depleted their input light, which can be used to advantage in the improved laser system described herein. For example, one of the undepleted fundamental harmonics 104 of the OP module 103 may be directed to a fifth-harmonic (5ω) generator module 105, which includes a number of frequency conversion stages and mixing stages to be generated by the fundamental harmonic 5th harmonic (described in more detail below with reference to Figures 2A and 2B).
Similarly, in an alternative embodiment, the fundamental harmonic 102 ′ may be first directed to the fifth harmonic generator module 105 to generate a fifth harmonic 106, and during the generation of the fifth harmonic 106 The undepleted fundamental harmonic 102 ′ (undepleted fundamental harmonic 104 ′) may be directed to the OP module 103 to be down-converted to the output frequency 107.
The output of the fifth harmonic generator module 105 (ie, the fifth harmonic 106) and the output frequency 107 may be combined (ie, mixed) in a mixing module 108. In one embodiment, the mixing module 108 may include (of the same type) one or more non-linear crystals, such as β-barium borate (BBO), lithium triborate (LBO), or hydrogen-annealed lithium cesium borate (CLBO) Crystal. The mixing module 108 generates a laser output 109 having a frequency of approximately 5.5ω and a corresponding wavelength of 193.368 nanometers (ie, the fundamental harmonic length divided by approximately 5.5).
The advantage of using Type I degenerate down-conversion is that no power is wasted during the generation of an unwanted wavelength or polarized light. If a fundamental harmonic laser with sufficient power at one wavelength of 5.5 times the desired output wavelength of approximately 193.368 nanometers is easily obtained at a reasonable cost, an embodiment including degenerate down-frequency conversion may be preferred. The advantage of non-degenerate down-conversion is that lasers with wavelengths between about 1064.0 nm and about 1064.6 nm can be easily obtained at power levels of tens of watts or 100 watts, which is not easy at this time. The level obtains a laser with a wavelength of substantially 1063.5 nm. Non-degenerate down-conversion allows easy access to high-power lasers to produce any desired output wavelength close to 193.368 nm.
FIG. 1B illustrates another exemplary laser system 130 for generating a UV wavelength of about 193.368 nanometers. In this embodiment, one of the fundamental harmonic lasers 110 operating at a fundamental harmonic frequency ω generates a fundamental harmonic 111. In one embodiment, the frequency ω may correspond to a wavelength of about 1063.5 nm, or in another embodiment, a wavelength between about 1064.0 nm and about 1064.6 nm. The fundamental harmonic 111 can be directed to a second harmonic generator module 112, which doubles the fundamental harmonic 111 to generate a second harmonic 113. An undepleted portion of the fundamental harmonic 111 from the second harmonic generator module 112 (ie, the undepleted fundamental harmonic 121) may be directed to a fifth harmonic generator module 116. The second harmonic 113 can be guided to an OP module 114. In some embodiments, the OP module 114 may include a non-linear crystal, such as periodically polarized lithium niobate, magnesium oxide-doped lithium niobate, or KTP. In some embodiments, the OP module 114 may include a low power laser, such as a diode laser or a low power fiber laser.
In a preferred embodiment, the OP module 114 generates an output frequency 120 including a signal of about 1.5ω and an idle frequency signal of about 0.5ω. Note that because the wavelengths of the signal and the idler signal are completely different in this embodiment, the signal and the idler signal can be easily separated using, for example, a dichroic coating, chirp, or grating. In some embodiments, the signal and the idler signal have substantially orthogonal polarization and can therefore be separated by, for example, a polarized beam splitter. In the laser system 130, a 0.5ω or about 0.5ω idle frequency signal is a frequency component of interest. For example, if the wavelength of the fundamental harmonic 111 is 1063.5 nanometers, the wavelength of the light output associated with the idle frequency signal converted by the down conversion of the OP module 114 is 2127 nanometers, which is twice the fundamental harmonic Wavelength 102. In another example, if the fundamental harmonic 102 has a wavelength of 1064.4 nanometers and the desired output wavelength is 193.368 nanometers, the idle frequency signal wavelength will be 2109.7 nanometers.
Note that in other embodiments, it is not necessary to separate the signal from the idle frequency signal because only the desired wavelengths in the mixing module 118 are properly phase-matched. That is, the mixing module 118 may be configured to receive both the signal and the idle frequency signal, but actually only uses the idle frequency signal (which is 0.5ω). Since the undesired wavelength in these embodiments is about one wavelength of 710 nm, no significant absorption is applied at these wavelengths for most of the nonlinear crystals in the mixing module 118, and therefore the undesired wavelength is not It is too likely to cause significant heating or other undesirable effects.
The fifth harmonic generator module 116 combines an undepleted second harmonic 115 and an undepleted fundamental harmonic 121 from one of the OP modules 114 to generate a fifth harmonic 117 (see, for example, FIGS. 3A and 3B). , An exemplary fifth harmonic generator module). A mixing module 118 mixes the 5th harmonic 117 and the idle frequency signal portion of the output frequency 120 to generate a laser output 119 of about 5.5ω. In one embodiment, the mixing module 118 may include one or more non-linear crystals, such as β-barium borate (BBO), LBO, or CLBO crystals.
Note that in a manner similar to one illustrated for the fundamental harmonics 102 and 102 'in FIG. 1A, in some embodiments of the laser system 130, the second harmonic 113' may be first directed to the fifth harmonic generation Device module 116, and the undepleted portion 115 'of the second harmonic is guided to the OP module 114, as shown by the dotted line.
FIG. 1C illustrates yet another exemplary laser system 140 for generating a UV wavelength of about 193.4 nanometers. In this embodiment, a fundamental harmonic laser 122 operating at a frequency ω generates a fundamental harmonic 123. In this embodiment, the frequency ω may correspond to a wavelength of about 1063.5 nanometers or a wavelength between about 1064.0 nanometers and about 1064.6 nanometers.
The fundamental harmonic 123 may be directed to a second harmonic generator module 124, which doubles the fundamental harmonic 123 to generate a second harmonic 125. The second harmonic 125 is guided to an OP module 126. In one embodiment, the OP module 126 generates an output frequency 129 including a signal of about 1.5ω and an idle frequency signal of about 0.5ω. In some embodiments, the OP module 126 may include a non-linear crystal, such as periodically polarized lithium niobate, magnesium oxide-doped lithium niobate, or KTP. In other embodiments, the OP module 126 may include a low power laser, such as a diode laser or a low power fiber laser. As discussed below, the signal portion (approximately 1.5ω) of the output frequency 129 is the frequency component of interest for the mixing module 131.
One of the OP modules 126's undepleted second harmonics 127 can be directed to a fourth-harmonic generator module 128. The fourth harmonic generator module 128 doubles the undepleted second harmonic 127 to generate a fourth harmonic 133.
In some embodiments, the second harmonic 125 'from the second harmonic generator 124 is first directed to the fourth harmonic generator 128, and the undepleted 2 from the fourth harmonic generator 128 is The second harmonic 127 'is directed to the OP module 126 for down-conversion.
In the laser system 140, the mixing module 131 combines the signal portion of the output frequency 129 with the fourth harmonic 133 to generate a laser output 132 having a wavelength of about 5.5ω. As mentioned above, due to the frequency difference between the signal and the idle frequency signal, the idle frequency signal does not need to be separated from the signal before being received by the mixing module 131. In one embodiment, the mixing module 131 may include operating at a temperature of approximately 120 ° C to combine the 4th harmonic 133 and the 1.5ω signal to achieve a non-critical phase matching BBO of 5.5ω output 132 or Crystals of potassium fluoroborate beryllium (KBBF).
FIG. 2A illustrates an exemplary fifth harmonic generator module 250. FIG. In this embodiment, a second harmonic generator 201 receives a fundamental harmonic 200 (ω) (or an undepleted fundamental harmonic) from a first stage outside the fifth harmonic generator module 250 and causes the The fundamental harmonic 200 is doubled to produce a second harmonic 202. A fourth harmonic generator 204 receives the second harmonic 202 and doubles the second harmonic 202 to generate a fourth harmonic 205. A fifth-harmonic generator 207 combines the fourth-harmonic 205 with an undepleted fundamental harmonic 203 from one of the second-harmonic generators 201 to generate a fifth-harmonic output 210. Note that one of the fourth harmonic generator 204 is not depleted, the second harmonic 206, one of the fifth harmonic generators 207 is not depleted, the fundamental harmonic 208, and one of the fifth harmonic generators 207 is not depleted. 4 The sub-harmonic 209 is not used in this embodiment and can therefore be separated from the output (if needed). In one embodiment, the undepleted fundamental harmonic 208 can be redirected to the OP module 103 of the figure as shown by the dashed line 104 'in FIG. 1A.
FIG. 2B illustrates another exemplary fifth harmonic generator module 260. In this embodiment, a second-harmonic generator 211 receives a fundamental harmonic 222 (ω) (or an undepleted fundamental harmonic) from a first stage outside the fifth-harmonic generator module and causes the fundamental The harmonic 222 is doubled to produce a second harmonic 212. The third-harmonic generator 214 combines the second-harmonic 212 and one of the second-harmonic generators 211 without depleting the fundamental harmonic 213 to generate a third-harmonic 215. A fifth harmonic generator 218 combines the third harmonic 215 and one of the third harmonic generators 214 without depleting the second harmonic 216 to generate a fifth harmonic output 219. Note that one of the third harmonic generator 214 does not deplete the fundamental harmonic 217, one of the fifth harmonic generator 218 does not deplete the second harmonic 220, and one of the fifth harmonic generator 218 does not deplete the third harmonic. Wave 221 is not used in this embodiment and can therefore be separated from the output (if needed). Note that in one embodiment, the undepleted fundamental harmonic 217 can be guided to the OP module 103 of the figure as shown by the dashed line 104 'in FIG. 1A.
FIG. 3A illustrates yet another exemplary fifth harmonic generator module 300. In this embodiment, a fourth-harmonic generator 302 receives a second-harmonic 301 from a first stage outside the fifth-harmonic generator module 300 and doubles the second-harmonic 301 to generate a fourth-harmonic. Wave 303. A fifth-order harmonic generator 305 combines the fourth-order harmonic 303 and a first-order fundamental harmonic 308 (or an undepleted fundamental harmonic) from an external first-order fifth-order harmonic generator module 300 to generate a fifth-order harmonic. Harmonic output 308. Note that one of the fourth harmonic generators 302 is not depleted, the second harmonic 304, one of the fifth harmonic generators 305 is not depleted, the fundamental harmonic 306, and one of the fifth harmonic generators 305 is not depleted. The sub-harmonic 307 is not used in this embodiment, and therefore can be separated from the output if needed. Note that in one embodiment, the undepleted second harmonic 304 can be directed to the OP module 114 of the figure as shown by the dotted line 115 'in FIG. 1B.
FIG. 3B illustrates yet another exemplary fifth harmonic generator module 310. In this embodiment, a third-harmonic generator 313 combines a first-order fundamental harmonic 311 (or an undepleted fundamental harmonic) from the first order external to the fifth-harmonic generator module 310 and also from the fifth The second harmonic generator module 310 is a second order harmonic 312 (or an undepleted second harmonic) outside the first order to generate a third harmonic 315. A fifth-harmonic generator 317 combines the third-harmonic 315 with an undepleted second-harmonic from one of the third-harmonic generators 313 to generate a fifth-harmonic output 320. Note that one of the third harmonic generator 313 does not deplete the fundamental harmonic 314, one of the fifth harmonic generator 317 does not deplete the second harmonic 318, and one of the fifth harmonic generator 317 does not deplete the third harmonic. Harmonics 319 are not used in this embodiment and can therefore be separated from the output if needed. Note that in one embodiment, the undepleted second harmonic 318 can be directed to the OP module 114 of the figure as shown by the dotted line 115 'in FIG. 1B.
FIG. 4 illustrates another exemplary laser system 400 for generating a UV wavelength of about 193.4 nanometers. In this embodiment, a fundamental harmonic laser 401 operating at a frequency ω generates a fundamental harmonic 402. An OP module 403 uses the fundamental harmonic 402 to generate a degenerate or non-degenerate output frequency 405. Therefore, for example, if the wavelength of the fundamental harmonic 402 is 1063.5 nm, the down-converted light wavelength of the output frequency is 2127 nm, which is twice the wavelength of the fundamental harmonic 402. In another example, if the wavelength of the fundamental harmonic 402 is 1064.4 nm and the desired output wavelength is 193.368 nm, the output frequency 405 will correspond to a signal wavelength of 2109.7 nm. In some embodiments, the OP module 403 may include a non-linear crystal, such as periodically polarized lithium niobate, magnesium oxide-doped lithium niobate, or KTP. In some embodiments, the OP module 403 may include a low power laser, such as a diode laser or a low power fiber laser.
A second harmonic generator 406 doubles one of the undepleted fundamental harmonics 404 from the OP module 403 to generate a second harmonic 407. A fourth harmonic generator 409 doubles the second harmonic 407 to generate a fourth harmonic 410. A mixing module 412 combines the output frequency 405 and the 4th harmonic 410 to generate a 4.5th harmonic 413, which has a wavelength of about 236 nm. A mixing module 416 mixes the approximately 4.5th harmonic 413 and one of the undepleted fundamental harmonics 408 from the second harmonic generator 406 to generate an approximately 5.5ω laser output having one of the wavelengths of approximately 193.368 nm 417.
Note that one of the fourth harmonic generators 409, the non-depleted second harmonic 411, the one from the mixing module 412, the undepleted 4th harmonic and the undepleted OP signal 414 are not used in this embodiment, and It can therefore be separated from the output (if required).
It should be further noted that the fundamental harmonic (ω) is used in three modules: a second harmonic generator 406, a mixing module 416, and an OP module 403. Various solutions for making full use of the undepleted fundamental harmonics from a generator or module are possible. For example, in some embodiments, the fundamental harmonic may include an undepleted fundamental harmonic 404 'from one of the second harmonic generators 406 instead of the fundamental harmonic laser 401 as shown by the fundamental harmonic 402 Provide directly to the OP module 403. Likewise, in some preferred embodiments, the fundamental harmonic (ω) 402 'may be provided directly to the second harmonic generator 406 to more easily generate more second harmonics 407. The undepleted fundamental harmonics 408 and / or 404 'output from the second harmonic generator 406 may be directed to the mixing module 416 and / or the OP module 403, respectively. In some embodiments, one of the undepleted fundamental harmonics 418 'from the mixing module 416 may be directed to the OP module 403.
It should be understood that the diagrams of various laser systems are intended to illustrate exemplary components / steps to produce a predetermined frequency output light from a predetermined frequency input light. For simplicity, the diagrams show the main optical modules and harmonic generators involved in this procedure. Therefore, the drawings are not intended to represent the actual physical layout of the components, and actual implementations will typically include additional optical elements.
For example, in any of the embodiments described herein, a mirror can be used as needed to guide fundamental or other harmonics. For example, other optical components such as chirped beams, beam splitters, beam combiners, and dichroic coating mirrors can be used to separate and combine beams as needed. Various combinations of mirrors and beam splitters can be used to separate and route various wavelengths between different harmonic generators and mixers in any suitable sequence. Lenses and / or curved mirrors may be used as appropriate to focus the beam waist to the focal point of a substantially circular or elliptical cross section inside or near the non-linear crystal. If necessary, chirped, grating, or diffractive optical elements can be used to separate different wavelengths at the output of the harmonic generator and the mixer module. Use different wavelengths at the input of the harmonic generator and mixer, as appropriate, using chirped, coated mirrors, or other components. Optionally use a beam splitter or coated mirror to separate wavelengths or split a wavelength into two beams. Filters can be used to block unwanted and / or undepleted wavelengths at the output of any stage. For example, a wave plate may be used to rotate the polarized light as needed to accurately align the polarized light of an input wavelength with respect to the axis of a non-linear crystal. From these drawings and their associated descriptions, those skilled in the art will understand how to construct a laser according to an embodiment.
Although the undepleted fundamental harmonics and undepleted harmonics (when a subsequent harmonic generator is not needed) are shown as being separate from the desired harmonics in the embodiments, in some cases even a subsequent harmonic generator There is no need for undepleted light, and it is acceptable to allow the light to pass to the harmonic generator. If the power density is sufficiently low without damaging components of this stage and if there is minimal interference with the desired frequency conversion procedure (for example, because phase matching at the crystal angle is not used), this transmission of undepleted light is acceptable. Those skilled in the art will understand various trade-offs and alternatives to determine if the undepleted fundamental harmonics / harmonics should be separated from the desired harmonics.
In one embodiment, at least one of the above-mentioned second harmonic generators may include an LBO crystal that is substantially non-critically phase-matched at a temperature of about 149 ° C to generate light of about 532 nm. In one embodiment, at least one of the third harmonic generators may include CLBO, BBO, LBO, or other non-linear crystals. In one embodiment, at least one of the above-mentioned fourth harmonic generator and fifth harmonic generator may use critical phase matching in CLBO, BBO, LBO, or other non-linear crystals. In some embodiments, a mixing module that mixes 5ω and about 0.5ω (such as 108 in FIG. 1A and 118 in FIG. 1B) may include a CLBO or an LBO crystal, which is related to a high Deff
(~ 1 pm / V) and a low walk-off angle (<45 mrad for CLBO and <10 mrad for LBO) are critically phase matched. In other embodiments, such as the mixing module 131 mixing 4ω and about 1.5ω in FIG. 1C or the mixing module 416 mixing about 4.5ω and fundamental harmonics in FIG. 4 may include a BBO or KBBF crystal.
In some embodiments, the fourth harmonic generator, the fifth harmonic generator, and / or the mixing module may advantageously use some or all of the methods and systems disclosed in the following applications: March 5, 2012 U.S. Patent Application No. 13 / 412,564 with application titled "Laser with high quality, stable output beam, and long-life high-conversion-efficiency non-linear crystal" and application titled "Mode" on July 22, 2011 -locked UV laser with high quality, stable output beam, long-life high conversion efficiency non-linear crystal and a wafer inspection system using a mode-locked laser '', U.S. Provisional Application No. 61 / 510,633 (and U.S. Patent Application 13 / 412,564 claims its priority), which are incorporated herein by reference.
In some embodiments, any of the harmonic generators discussed herein may advantageously include a hydrogen-annealed nonlinear crystal. These crystals can be processed as described in the following applications: US Patent Application No. 13 / 488,635 entitled "Hydrogen Passivation of Nonlinear Optical Crystals" by Chuang et al., Filed June 1, 2012, and in 2011 US Provisional Application No. 61 / 544,425 entitled "Improvement of NLO Crystal Properties by Hydrogen Passivation" filed by Chuang et al. On October 7. These applications are incorporated herein by reference. Hydrogen-annealed crystals can be particularly useful in this class involving deep UV wavelengths (e.g., fourth and fifth harmonic generators and mixing modules).
Note that in some embodiments, a mixing module of a mixed OP module signal frequency or idle frequency signal frequency and a fourth harmonic or a fifth harmonic is placed inside the OP module. This avoids the need to take the signal frequency or idle frequency signal out of the OP module. It also has the advantage of making the highest signal or idle signal (as appropriate) power levels available for mixing, thereby making the mixing more efficient.
In one embodiment, to generate sufficient power at a fundamental harmonic (eg, about 1063.5 nm wavelength), one or more amplifiers may be used to increase the power of the fundamental harmonic. If two or more amplifiers are used, a sub-laser can be used to inoculate the amplifiers, thereby ensuring that all amplifiers output the same wavelength and have synchronized output pulses. For example, FIG. 5 illustrates an exemplary one of the fundamental harmonic laser 500 including one of the seed laser (stabilized narrowband laser) 503 that includes one of the seed light generating the desired fundamental harmonic length (e.g., approximately 1063.5 nm). configuration. The seed laser 503 can be implemented by, for example, a neodymium-doped YAG laser, a neodymium-doped yttrium vanadate laser, an optical fiber laser, or a stabilized diode laser.
The amplifier 502 amplifies the seed light to a higher power level. In one embodiment, the amplifier 502 may include a neodymium-doped YAG, a neodymium-doped yttrium vanadate, or a neodymium-doped mixture of hafnium vanadate and yttrium vanadate. In other embodiments, the amplifier 502 may include an erbium-doped fiber amplifier. An amplifier pump 501 can be used to pump the amplifier 502. In an embodiment, the amplifier pump 501 may include one or more diode lasers operating at a wavelength of about 808 nanometers.
Because multiple frequency conversion stages may require fundamental harmonic laser wavelengths (depending on the output power required at approximately 193.4 nm wavelength), more fundamental harmonic laser light is required than light that can be conveniently generated by a single amplifier . In these cases, multiple amplifiers can be used. For example, in the fundamental harmonic laser 500, an amplifier 506 and an amplifier pump 507 may be provided in addition to the amplifier 502 and the amplifier pump 501. Like the amplifier 502, the amplifier 506 can also amplify the seed light to a higher power. Amplifier pump 507 can pump amplifier 506.
In one or more amplifier embodiments, each amplifier may generate its own fundamental harmonic laser output. In FIG. 5, the amplifier 502 may generate a fundamental harmonic laser output (fundamental harmonic) 508 and the amplifier 506 may generate a fundamental harmonic laser output (fundamental harmonic) 509. In this configuration, the fundamental harmonics 508 and 509 can be directed to different frequency conversion stages. Note that to ensure that the fundamental harmonics 508 and 509 have the same and synchronized wavelengths, the seed laser 503 should provide the same seed light to the amplifiers 502 and 506. The amplifiers 502 and 506 should be substantially the same and the amplifier pumps 501 and 507 should be substantially the same. . To ensure that the same seed light is provided to both the amplifiers 502 and 506, a beam splitter 504 and a mirror 505 can split the seed light and direct one of its fractions to the amplifier 506. Although only two amplifiers are shown in FIG. 5, other embodiments of a fundamental harmonic laser may include more amplifiers, amplifier pumps, beam splitters, and mirrors in a similar configuration to generate multiple fundamental harmonic outputs.
FIG. 6 illustrates one exemplary degenerate OPA 600 that produces infrared light 606 that is twice the fundamental harmonic length (ie, half the fundamental harmonic frequency). In this embodiment, a beam combiner 602 combines a fundamental harmonic 603 (for example, 1063.5 nm) with seed light generated by a sub-laser 601. In one embodiment, the beam combiner 602 may include a dichroic coating that effectively reflects one wavelength while transmitting another wavelength. In another embodiment, the beam combiner 602 may be a polarized beam combiner that effectively combines one of two substantially orthogonally polarized lights. In the configuration shown in FIG. 6, the two wavelengths can progress substantially collinearly through a non-linear converter 604. The non-linear converter 604 may include periodically polarized lithium niobate, magnesium oxide-doped lithium niobate, KTP, or other suitable non-linear crystalline materials.
In an embodiment, the seed laser 601 may be a low-power laser (eg, a diode laser or a low-power fiber laser), which generates a seed wavelength that is twice the wavelength of the fundamental harmonic laser ( For example, if the fundamental harmonic laser is 1063.5 nm, the seed wavelength is 2127 nm). This wavelength can be used to inoculate a down-conversion procedure in the OPA 600. A laser diode can be based on a compound semiconductor such as GaInAs, InAsP, or GaInAsSb, where a suitable composition matches the band gap of the compound semiconductor to approximately 0.5829 electron volts of a 2127 nanometer photon. In this diode configuration, the power of the seed laser 601 need only be about 1 milliwatt, several milliwatts, or tens of milliwatts. In one embodiment, the seed laser 601 can be stabilized by using, for example, a grating and a stabilization temperature. The seed laser 601 can generate polarized light, which is introduced into a non-linear crystal (of the non-linear converter 604) and the polarized light is substantially perpendicular to the fundamental harmonics. In another embodiment, a non-linear crystal (of the non-linear converter 604) may be included in a resonant cavity to generate a laser / amplifier based on spontaneous emission. In one embodiment, the output wavelength 606 can be separated from an undepleted fundamental harmonic 607 using a beam splitter or chirp 605.
One of the advantages of using an OPA for degenerate down-conversion is that inoculating the OPA with a narrow-band stabilized seed laser signal will result in a narrow-band output transmitted by excitation. This overcomes the natural tendency of degenerate down-conversion to produce a wide-band output (depending on the non-linear crystal), because the signals and idle frequency signals that are phase-matched in the non-linear crystal can be generated spontaneously in any wavelength range. In an OPO, it is often difficult to fabricate a high reflectance (or optionally transmittance) in a narrow frequency band of interest (usually one-tenth of a nanometer in the laser system disclosed herein) but Filters with extremely low reflectance (or transmittance) outside the narrow band.
Other embodiments of an OPA may use a photonic crystal fiber to generate a wavelength that is substantially twice the wavelength of the fundamental harmonic. One other embodiment of OPA may use a seed laser diode operating at about 2127 nanometers to inoculate (non-linear converter 604) a photonic crystal fiber down-converter. It may be more effective to use a non-linear optical crystal for down-conversion because the non-linear crystal system (of non-linear converter 604)(2)
Program instead of a chi(3)
program. However, a photonic crystal can be used in some situations.
Note that a laser can start at a wavelength that is not exactly equal to 5.5 times the output wavelength. For example, one of the fundamental harmonics may have a wavelength of about 1064.4 nanometers, and the desired output wavelength is close to 193.368 nanometers. In this case, instead of using degenerate down-conversion, two different output wavelengths (ie, the signal and the idle signal) can be generated by an OPO or OPA. Because these two wavelengths are close together (e.g., a few nanometers or tens of nanometers are separated in some embodiments), type II frequency conversion can be used (if phase matching can be achieved), so that the signal and idler signal have Vertically polarized light and can be separated by a polarized beam splitter. In other embodiments, a standard gauge (or appropriately designed volume Bragg grating) of appropriate length may be used to reflect or transmit a desired wavelength while (optionally) not reflecting or transmitting another wavelength.
FIG. 7 illustrates one exemplary non-degenerate OPA 700 that generates infrared light 706 that is slightly shifted from twice the fundamental harmonic length (ie, half of the fundamental harmonic frequency). In this embodiment, a beam combiner 702 combines a fundamental harmonic 703 (for example, 1064.4 nm) with seed light generated by a sub-laser 701 (if the fundamental harmonic is 1064.4 nm and the desired laser system output The wavelength is 193.368 nanometers, and the seed light wavelength is (for example, 2109.7 nanometers). This fundamental harmonic length can be generated by a neodymium-doped YAG laser, a neodymium-doped yttrium vanadate laser, a neodymium-doped vanadium and yttrium vanadate-doped neodymium mixture laser, or an erbium-doped fiber laser. In one embodiment, the beam combiner 702 may include a dichroic coating or a diffractive optical element that efficiently reflects one wavelength while effectively transmitting another wavelength. In this configuration, the two wavelengths can progress substantially collinearly through a non-linear converter 704. Non-linear converter 704 may include periodically polarized lithium niobate, magnesium oxide-doped lithium niobate, KTP, or other suitable non-linear crystalline materials. The non-linear converter 704 can amplify the seed wavelength and also generate a second wavelength (if the fundamental harmonic length is 1064.4 nm and the seed wavelength is 2109.7 nm, the second wavelength will be approximately equal to 2148.2 nm).
An element 705 such as an output beam splitter, filter, standard gage, or diffractive optical element may be used to separate an undesired (e.g., about 2148.2 nm) wavelength 707 from the desired (approximately 2109.7 nm) wavelength 706. If desired, element 705 can also be used to separate any undepleted fundamental harmonics from output beam 706. In some embodiments, an idle frequency signal wavelength (such as 2148.2 nm) may be seeded instead of the signal wavelength. Note that when inoculating the idle frequency signal, the signal bandwidth is determined by the bandwidth of both the fundamental harmonic laser and the seed laser, and when inoculating the signal, the frequency of the signal is largely determined by the radio frequency of the seed laser. width.
After separating these two wavelengths, the signal frequency (e.g., the wavelength is 2109.7 nm) can be mixed with the fifth harmonic of the fundamental harmonic (e.g., one of the wavelengths is substantially 212.880 nm) to produce substantially 193.368 nm One meter output wavelength. This mixing can be done after any of the above embodiments or their equivalents. Alternatively, the substantially 2109.7 nanometer wavelength may be mixed with the fourth harmonic of the fundamental harmonic (one of which is substantially 266.1 nanometers) to produce substantially 236.296 nanometers of light. This can then be mixed with the fundamental harmonic (or an undepleted fundamental harmonic) to produce substantially one output wavelength of 193.368 nanometers. This mixing can be done after any of the embodiments shown in Figure 4 or its equivalent.
For fundamental harmonic lasers, a high repetition rate laser (such as a mode-locked laser operating at about 50 MHz or higher repetition rate) can be used to construct a quasi-CW laser operation. For fundamental harmonic lasers, a CW laser can be used to construct a real CW laser. A CW laser may require one or more of the frequency conversion stages contained in the resonant cavity to add power density sufficient to obtain effective frequency conversion.
8 to 15 illustrate a system that may include the above-mentioned laser system using an OP module for frequency conversion. These systems can be used in photomasks, reduction masks, or wafer inspection applications.
FIG. 8 illustrates an exemplary optical inspection system 800 for inspecting the surface of a substrate 812. The system 800 generally includes a first optical configuration 851 and a second optical configuration 857. As shown, the first optical configuration 851 includes at least one light source 852, detection optics 854, and reference optical device 856, and the second optical configuration 857 includes at least transmitted light optics 858, transmitted light detector 860, and reflected light optics. Device 862 and reflected light detector 864. In a preferred configuration, the light source 852 includes one of the improved lasers described above.
The light source 852 is configured to emit a light beam traveling through an acousto-optic device 870 configured to deflect and focus the light beam. The acousto-optic device 870 may include a pair of acousto-optic elements (for example, an acousto-optic pre-scanner and an acousto-optic scanner) that deflect the light beam in the Y direction and focus it in the Z direction. For example, most acousto-optic devices send an RF signal to quartz or a crystal (such as TeO2
) While operating. This RF signal causes an acoustic wave to advance through the crystal. The crystal becomes asymmetric due to the advancing sound waves, causing the refractive index to change throughout the crystal. This change causes the incident beam to form a focused forward spot that is deflected in an oscillating manner.
When the light beam is emitted from the acousto-optic device 870, the light beam then travels through a pair of quarter wave plates 872 and a relay lens 874. The relay lens 874 is configured to collimate the light beam. The collimated beam then continues on its path until it reaches a diffraction grating 876. Diffraction grating 876 is configured to flare out the beam and more specifically to split the beam into three distinct beams that are spatially distinguishable from each other (ie, spatially distinct). In most cases, these spatially distinct beams are also configured to be equally spaced and have substantially equal light intensities.
After the three beams leave the diffraction grating 876, they travel through an aperture 880 and then continue until they reach a beam splitter cube 882. The beam splitter cube 882 (in conjunction with the quarter-wave plate 872) is configured to split the beams into two paths, one path leading down and the other path to the right (the group shown in FIG. 8 State). A path guided downward is used to distribute a first light portion of the light beams to the substrate 812, and a path guided to the right is used to distribute a second light portion of the light beams to the reference optics 856. In most embodiments, most of the light is distributed to the substrate 812 and a smaller percentage of light is distributed to the reference optics 856, but the percentage ratio may be changed according to the specific design of each optical detection system. In an embodiment, the reference optics 856 may include a reference light collecting lens 814 and a reference detector 816. The reference light collecting lens 814 is configured to collect a portion of the light beam and guide the portion of the light beam to a reference detector 816, which is configured to measure light intensity. Reference optics are generally well known in the art and will not be discussed in detail for simplicity.
The three beams directed downward from the beam splitter 882 are received by a telescope 888, which contains lens elements that redirect and expand the light. In one embodiment, the telescope 888 is part of a telescope system comprising a plurality of telescopes rotating around a transposition. For example, three telescopes can be used. The purpose of these telescopes is to change the size of the scanning spot on the substrate and thereby allow the selection of the smallest detectable defect size. More specifically, each of these telescopes generally represents a different pixel size. Thus, one telescope can produce a larger spot size, making detection faster and less sensitive (e.g., low resolution), while another telescope can produce a smaller spot size, making detection slower and More sensitive (for example, high resolution).
Viewed from a telescope 888, the three beams travel through an objective lens 890 configured to focus the beams onto a surface of the substrate 812. When these beams intersect with the surface into three different light spots, both a reflected beam and a transmitted beam can be generated. The transmitted light beams travel through the substrate 812, and the reflected light beams are reflected from the surface. For example, the reflected beams can be reflected from an opaque surface of the substrate, and the transmitted beams can be transmitted through a transparent region of the substrate. The transmitted light beams are collected by transmitted light optics 858 and the reflected light beams are collected by reflected light optics 862.
Regarding transmitted light optics 858, the transmitted light beams are collected by a first transmission lens 896 and focused onto a transmission 稜鏡 810 with the help of a spherical aberration corrector lens 898 after traveling through the substrate 812. The 稜鏡 810 may be configured to have one of the facets for each of the transmitted beams, and the facet is configured to reposition and bend the transmitted beams. In most cases, the R & S®810 is used to split the beams such that they each land on a single detector in a transmitted light detector configuration 860 (shown as having three distinct detectors). Therefore, after the light beams leave 稜鏡 810, they travel through a second transmission lens 802, which individually focuses each of the separated light beams onto one of the three detectors. Each of the three detectors is configured to measure the intensity of transmitted light.
Regarding the reflected light optics 862, the reflected light beams are collected by the objective lens 890 after reflecting from the substrate 812, which then directs the light beams toward the telescope 888. The beams also travel through a quarter-wave plate 804 before reaching the telescope 888. In general, the objective lens 890 and the telescope 888 manipulate the collection beam in one of the optically reversed ways as to how to manipulate the incident beam. That is, the objective lens 890 re-collimates the light beams, and the telescope 888 reduces its size. When the beams leave the telescope 888, they continue (backward) until they reach the beam splitter cube 882. The beam splitter 882 is configured to operate with the quarter wave plate 804 to direct the beams onto a central path 806.
Then, the light beams continuing on the path 806 are collected by a first reflection lens 808, and the first reflection lens 808 focuses each of the light beams onto a reflection 稜鏡 809, which includes the reflection 该等 809. Facets of one of the reflected beams. Reflective 稜鏡 809 is configured to relocate and bend the reflected beams. Similar to transmission 稜鏡 810, reflection 稜鏡 809 is used to separate the beams so that they each fall on a single detector in a reflected light detector configuration 864. As shown, the reflected light detector configuration 864 includes three individual distinct detectors. When the light beams leave the reflection 稜鏡 809, they travel through a second reflection lens 811, which individually focuses each of the separated light beams onto one of these detectors. Each of the detectors is configured to measure the intensity of the reflected light.
There are multiple detection modes that can be facilitated by the aforementioned optical assembly. For example, the optical assembly can facilitate a transmitted light detection mode, a reflected light detection mode, and a simultaneous detection mode. Regarding the transmitted light detection mode, the transmission mode detection is generally used for defect detection on a substrate such as a conventional optical mask having a transparent area and an opaque area. When the light beam scans the mask (or the substrate 812), light penetrates the mask at a transparent point and is detected by a transmitted light detector 860, which are positioned behind the mask and measured. The intensity of each of the light beams collected by the transmission light optics 858 including the first transmission lens 896, the second transmission lens 802, the spherical aberration lens 898, and 稜鏡 810 was measured.
Regarding the reflected light detection mode, reflected light detection can be performed on a transparent or opaque substrate containing image information in the form of chromium, developing photoresist, and other features. The light reflected by the substrate 812 travels backward along the same optical path as the detection optics 854, but then is turned into the detector 864 by a polarized beam splitter 882. More specifically, the first reflecting lens 808, 稜鏡 809, and the second reflecting lens 811 project light from the steered beam onto the detector 864. Reflected light detection can also be used to detect contamination on the top of the surface of an opaque substrate.
Regarding the simultaneous detection mode, both transmitted light and reflected light are used to determine the existence and / or type of a defect. The two measured values of the system are the intensity of the light beam transmitted through the substrate 812 as sensed by the transmitted light detector 860 and the intensity of the reflected light beam as detected by the reflected light detector 864. Then, the two measurements can be processed to determine the type of defect (if any) at a corresponding point on the substrate 812.
More specifically, simultaneous transmission and reflection detection can reveal the presence of an opaque defect detected by the transmission detector, and the output of the reflection detector can be used to reveal the type of defect. As an example, a chromium dot or a particle on a substrate can cause a low transmitted light indication from a transmission detector, but a reflected chromium defect can cause a high reflected light indication from a reflected light detector and a Particles can cause a lower reflected light indication from one of the same reflected light detectors. Therefore, by using both reflection and transmission detection, a particle on top of the chrome geometry can be located. If only the reflection or transmission characteristics of the defect are checked, this positioning cannot be performed. In addition, signals for certain types of defects can be determined, such as the ratio of their reflected light intensity to transmitted light intensity. This information can then be used to automatically classify defects. US Patent 5,563,702, issued October 8, 1996 and incorporated herein by reference, describes additional details regarding system 800.
According to some embodiments of the present invention, there is a detection system of about 193 nm laser system which can simultaneously detect two data channels on a single detector. Such an inspection system can be used to inspect a substrate such as a reticle, a reticle, or a wafer, and may be a U.S. patent issued by Brown et al. On May 5, 2009 and incorporated herein by reference. No. 7,528,943.
FIG. 9 shows a reticle, photomask, or wafer inspection system 900 that simultaneously detects one of two image or signal channels on a sensor 970. The illumination source 909 does not have a 193 nm laser system as described herein. The light source may further include a pulse multiplier and / or a coherence reduction scheme. When a detected object 930 is transparent (such as a double reduction mask or reticle), the two channels may include reflection intensity and transmission intensity, or may include two different illumination modes, such as angle of incidence, polarization state, Wavelength range or some combination thereof.
As shown in FIG. 9, the illumination relay optics 915 and 920 relay the illumination from the source 909 to the detected object 930. The detected object 930 may be a double-shrink mask, a photomask, a semiconductor wafer, or other items to be detected. The image relay optics 955 and 960 relay the light reflected and / or transmitted by the detected object 930 to the sensor 970. The data corresponding to the detection signals or images of the two channels are displayed as data 980 and transmitted to a computer (not shown) for processing.
FIG. 10 illustrates an exemplary detection system 1000 including a plurality of objective lenses and one of the improved lasers described above. In the system 1000, illumination from a laser source 1001 is sent to multiple sections of the illumination subsystem. One of the first sections of the lighting subsystem contains elements 1002a to 1006a. The lens 1002a focuses the light from the laser 1001. The light from the lens 1002a is then reflected from the mirror 1003a. For illustration purposes, the mirror 1003a is placed at this location and can be positioned elsewhere. The light from the mirror 1003a is then collected by a lens 1004a forming an illumination pupil plane 1005a. Depending on the requirements of the detection mode, an aperture, filter, or other device to modify light may be placed in the pupil plane 1005a. The light from the pupil plane 1005a then travels through the lens 1006a and forms an illumination field plane 1007.
A second section of one of the lighting subsystems contains elements 1002b to 1006b. The lens 1002b focuses the light from the laser 1001. The light from lens 1002b is then reflected from mirror 1003b. The light from the mirror 1003b is then collected by a lens 1004b forming an illumination pupil plane 1005b. Depending on the requirements of the detection mode, an aperture, filter, or other device to modify light may be placed in the pupil plane 1005b. Light from the pupil plane 1005b then travels through the lens 1006b and forms an illumination field plane 1007. The light from this second segment is then redirected by a mirror or reflective surface such that the illumination field light energy at the illumination field plane 1007 includes the combined illumination segment.
The field plane light is then collected by a lens 1009 before being reflected from a beam splitter 1010. The lenses 1006a and 1009 form an image of the first illumination pupil plane 1005a at the objective pupil plane 1011. Similarly, the lenses 1006b and 1009 form an image of the second illumination pupil plane 1005b at the objective pupil plane 1011. An objective lens 1012 (or alternatively 1013) then acquires pupil light and forms an image of an illumination field 1007 at the sample 1014. The objective lens 1012 or the objective lens 1013 may be positioned close to the sample 1014. The sample 1014 can be moved (not shown) on a stage to position the sample in a desired position. The light reflected and scattered from the sample 1014 is collected by the high NA fold reflection objective lens 1012 or the objective lens 1013. After a reflective pupil is formed at the objective pupil plane 1011, the light energy passes through the beam splitter 1010 and the lens 1015 before an internal field 1016 is formed in the imaging subsystem. The internal imaging field is an image of the sample 1014 and the corresponding illumination field 1007. This field can be spatially separated into multiple fields corresponding to the illuminated field. Each of these fields can support a single imaging mode.
One of these fields can be redirected using mirror 1017. The redirected light then travels through the lens 1018b before forming another imaging pupil 1019b. The imaging pupil is an image of the pupil 1011 and the corresponding illumination pupil 1005b. Depending on the requirements of the detection mode, an aperture, filter, or other device used to modify light may be placed in the pupil plane 1019b. The light from the pupil plane 1019b then travels through the lens 1020b and forms an image on the sensor 1021b. In a similar manner, the light passing through the mirror or reflective surface 1017 is collected by the lens 1018a and forms an imaging pupil 1019a. The light from imaging pupil 1019a is then collected by lens 1020a before forming an image on detector 1021a. The light imaged on the detector 1021a may be used in an imaging mode different from the light imaged on the sensor 1021b.
The lighting subsystem used in the system 1000 is composed of a laser source 1001, light collection optics 1002 to 1004, a beam shaping component placed close to a pupil plane 1005, and relay optics 1006 and 1009. An inner field plane 1007 is positioned between the lenses 1006 and 1009. In a preferred configuration, the laser source 1001 may include one of the improved lasers described above.
Regarding the laser source 1001, although illustrated as a single uniform block with one of two transmission points or angles, this actually means that it can provide two illumination channels (e.g., a first light energy channel (such as a first frequency One of the laser light sources that travels through the elements 1002a to 1006a) and a second optical energy channel (such as the laser light energy that travels through the elements 1002b to 1006b at a second frequency). Different light energy modes can be used, such as a bright field mode in one channel and a dark field in another channel.
Although the light energy from the laser source 1001 is shown to be emitted at 90-degree intervals and the elements 1002a to 1006a and 1002b to 1006b are oriented at a 90-degree angle, the light can actually be emitted in various orientations (not necessarily two-dimensional) and The components may be oriented differently than shown. Therefore, FIG. 10 is only represented by one of the components used and the angles or distances shown are not drawn to scale and are not design specific requirements.
Elements placed close to the pupil plane 1005 can be used in current systems that use the concept of aperture shaping. With this design, you can achieve uniform or near-uniform lighting as well as individual point lighting, ring lighting, quadrupole lighting, or other desired patterns.
Various implementations of the objective lens can be employed in a general imaging subsystem. A single fixed objective can be used. This single objective lens supports all desired imaging and inspection modes. This design can be achieved if the imaging system supports a relatively large field size and a relatively high numerical aperture. The numerical aperture can be reduced to a desired value by using internal apertures placed at the pupil planes 1005a, 1005b, 1019a, and 1019b.
Multiple objective lenses can also be used as shown in FIG. 10. For example, although two objective lenses 1012 and 1013 are shown, any number of objective systems are possible. The objective lenses in this design can be optimized for each wavelength generated by the laser source 1001. These objective lenses 1012 and 1013 may have a fixed position or move into a position close to the sample 1014. To move multiple objectives in close proximity to the sample, a rotating swivel can be used as is common on standard microscopes. Other designs for moving the objective lens near a sample can be used. These designs include (but are not limited to) translating the objective lenses laterally on an objective table and using a goniometer to translate the objective lenses in an arc. In addition, any combination of fixed objective lenses and multiple objective lenses on a turntable can be achieved according to this system.
The maximum numerical aperture of this configuration can approach or exceed 0.97, but can be higher in some cases. The large range of illumination and collection angles that this high NA refracting imaging system may have combined with its large field size allows the system to support multiple detection modes simultaneously. As can be understood from the previous paragraph, multiple imaging modes can be implemented using a single optical system or a machine with a lighting device. The high NA revealed for illumination and collection allows the imaging mode to be implemented using the same optical system, thereby allowing imaging to be optimized for different types of defects or samples.
The imaging subsystem also includes intermediate image forming optics 1015. The purpose of the image forming optics 1015 is to form an internal image 1016 of one of the samples 1014. At this internal image 1016, a mirror 1017 can be placed to redirect light corresponding to one of these detection modes. The light at this location can be redirected because the light used for imaging mode is spatially separated. Image forming optics 1018 (1018a and 1018b) and 1020 (1020a and 1020a) can be implemented in several different forms (including varifocal zoom, multiple afocal tube lenses with focusing optics, or multiple image forming mag tubes). 1020b). US Published Application 2009/0180176, published on July 16, 2009 and incorporated herein by reference, describes additional details regarding system 1000.
FIG. 11 illustrates an exemplary ultra-wideband UV microscope imaging system 1100 including one of three sub-segments 1101A, 1101B, and 1101C. The sub-section 1101C includes a fold-reflection objective section 1102 and a zoom tube lens 1103. The fold-reflection objective lens section 1102 includes a fold-reflection lens group 1104, a field lens group 1105, and a focusing lens group 1106. The system 1100 can image an object / sample 1109 (eg, a wafer being inspected) onto an image plane 1112.
The refracting lens group 1104 includes an approximately planar (or planar) reflector (which is a reflective coating lens element), a meniscus lens (which is a refractive surface), and a concave spherical reflector. The two reflective elements may have a central optical aperture without a reflective material to allow light from an intermediate image to travel through the concave spherical reflector and be reflected to the concave spherical reflector by the approximately planar (or planar) reflector. Up and travel back through the approximate plane (or plane) reflector to traverse the associated lens element or several associated lens elements on the way. The fold-reflection lens group 1104 is positioned to form a real image of the intermediate image, so that the primary longitudinal color of the system is substantially corrected in the wavelength band in combination with the zoom tube lens 1103.
The field lens group 1105 may be made of two or more different refractive materials, such as fused silicon and fluorinated glass, or a diffractive surface. The field lens groups 1105 may be optically coupled together or may be slightly spaced apart in the air. Because the dispersion of fused silicon and fluorinated glass is not substantially different in the deep ultraviolet range, the individual powers of several component elements of the field lens group must be of high magnitude to provide different dispersion. The field lens group 1105 has a net positive power aligned along an optical path near the intermediate image. The use of such a faded field lens allows a full correction of chromatic aberrations including at least secondary longitudinal colors and primary and secondary lateral colors over an ultra-wide spectral range. In one embodiment, only one field lens assembly needs to have a refractive material that is different from one of the other lenses of the system.
Focusing lens group 1106 includes a plurality of lens elements preferably all formed from a single type of material, wherein the refractive surface has a curvature selected to correct both monochromatic aberrations and color variations of the aberrations and focus light to an intermediate image And location. In one embodiment of the focusing lens group 1106, a combination of one of the lenses 1113 having low power corrects the chromatic variation of spherical aberration, coma aberration, and astigmatism. A beam splitter 1107 provides an entrance to a UV light source 1108. The UV light source 1108 can be advantageously implemented with the improved laser described above.
The zoom tube lens 1103 may all be the same refractive material (such as fused silicon) and be designed so that the primary longitudinal color and primary lateral color are not changed during zooming. These primary chromatic aberrations do not need to be corrected to zero and cannot be corrected to zero when only one glass type is used, but they must be fixed, which is feasible. The design of the refracting objective segment 1102 must then be modified to compensate for these uncorrected but fixed chromatic aberrations of the zoom tube lens 1103. The zoom tube lens 1103, which can zoom or change the magnification without changing its high-order chromatic aberration, includes a lens surface disposed along one of the optical paths of the system.
In a preferred embodiment, the zoom tube lens 1103 is first corrected independently of the refracting objective 1102 section using two refractive materials such as fused silicon and calcium fluoride. Next, the zoom tube lens 1103 and the refracting objective lens section 1102 are combined. At this time, the refracting objective lens section 1102 can be modified to compensate the residual high-order chromatic aberration of the system 1100. Due to the field lens group 1105 and the low power lens group 1113, this compensation is feasible. Next, optimizing the combined system allows all parameters to be changed to achieve the best performance.
Note that sub-segments 1101A and 1101B contain components substantially similar to sub-segment 1101C and are therefore not discussed in detail.
The system 1100 includes a group of folding mirrors 1111 to provide a linear zoom motion that allows zooming from one of 36X to 100X. Large range zoom provides continuous magnification change, while fine zoom reduces frequency overlap and allows electronic image processing, such as inter-cell subtraction for a repeating image array. The folding mirror group 1111 can be characterized as a "trombone" system which is a reflective element. Zooming is accomplished by moving the group of zoom tube lenses 1103 as a unit and also moving the arm of the long U-shaped slide tube. Because the trombone movement only affects focus and the f # speed at its location is extremely low, the accuracy of this movement may be extremely loose. One advantage of this trombon configuration is that it significantly shortens the system. Another advantage is that there is only one zoom motion involving one of the active (non-flat) optical elements. And another zoom movement of the long U-shaped slider is not sensitive to errors. US Patent 5,999,310, issued on December 7, 1999 and incorporated herein by reference, describes the system 1100 in further detail.
FIG. 12 illustrates adding a normal incident laser illumination (dark field or bright field) to a fold reflection imaging system 1200. The lighting block of the system 1200 includes: a laser 1201; an adaptation optical device 1202, which is used to control the size and contour of the illumination beam on the detected surface; an aperture and window 1203, which is in a mechanical housing 1204;稜鏡 1205, which is used to redirect the laser incident on the surface of the specimen 1208 with the normal line along the optical axis.稜鏡 1205 also guides the specular reflection from the surface features of sample 1208 and the reflection from the optical surface of an objective lens 1206 to an image plane 1209 along the optical path. The lens for the objective lens 1206 may be provided in the general form of a fold-reflection objective lens, a focusing lens group, and a zoom tube lens group (see FIG. 11). In a preferred embodiment, the laser 1201 can be implemented by the improved laser. Published patent application 2007/0002465, published on January 4, 2007 and incorporated herein by reference, describes the system 1200 in further detail.
FIG. 13A illustrates an area-surface detection device 1300 for detecting a surface 1311, which includes an illumination system 1301 and a light collection system 1310. As shown in FIG. 13A, a laser system 1320 directs a light beam 1302 through a lens 1303. In a preferred embodiment, the laser system 1320 includes one of the improved laser, an annealed crystal, and an annealed condition that maintains the crystal during low temperature standard operation. The first beam shaping optics can be configured to receive a beam from a laser and focus the beam to an elliptical cross section at a beam waist in or near the crystal.
The lens 1303 is oriented such that its principal plane is substantially parallel to the same surface 1311 and thus an illumination line 1305 is formed on the surface 1311 in the focal plane of the lens 1303. In addition, the light beam 1302 and the focused light beam 1304 are guided to the surface 1311 at a non-orthogonal incidence angle. Specifically, the light beam 1302 and the focused light beam 1304 may be guided to the surface 1311 at an angle between about 1 degree and about 85 degrees with a normal direction. In this manner, the illumination light 1305 is substantially in the incident plane of the focused light beam 1304.
The light collection system 1310 includes a lens 1312 for collecting light scattered from the illumination line 1305 and a device for focusing the light generated by the lens 1312 to a device (such as a charge coupled device (CCD) 1314 including an array of photosensitive detectors)上 的 镜 1313。 On the lens 1313. In one embodiment, the CCD 1314 may include a linear array of detectors. In these cases, the linear array of detectors within the CCD 1314 may be oriented parallel to the illumination line 1305. In an embodiment, a plurality of light collection systems may be included, wherein each of the light collection systems includes similar components but with different orientations.
For example, FIG. 13B illustrates an exemplary array of light collection systems 1331, 1332, and 1333 for a surface inspection device (where the lighting system is not shown for simplicity, such as, similar to lighting system 1301). The first optical device in the light collection system 1331 collects light on a surface scattered from the sample 1311 in a first direction. The second optics in the light collection system 1332 collects light scattered from the surface of the sample 1311 in a second direction. The third optics in the light collection system 1333 collects light scattered from the surface of the sample 1311 in a third direction. Note that the first path, the second path, and the third path have different reflection angles from the surface of the sample 1311. A platform 1312 that supports one of the samples 1311 can be used to cause relative movement between the optics and the sample 1311, so that the entire surface of the sample 1311 can be scanned. US Patent 7,525,649, issued on April 28, 2009 and incorporated herein by reference, further describes the surface inspection device 1300 and other multiple light collection systems.
FIG. 14 illustrates a surface detection system 1400 that can be used to detect anomalies on a surface 1401. In this embodiment, the surface 1401 may be partially illuminated by one of the laser systems 1430 including a laser beam generated by the improved laser beam described above. The output of the laser system 1430 can continuously travel through the polarizing optics 1421, a beam expander and aperture 1422, and the beam shaping optics 1423 to expand and focus the beam.
The resulting focused laser beam 1402 is then reflected by a beam folding assembly 1403 and a beam deflector 1404 to direct the beam 1405 toward the surface 1401 for illuminating the surface. In a preferred embodiment, the light beam 1405 is substantially normal or perpendicular to the surface 1401, but in other embodiments the light beam 1405 may be at an angle to the surface 1401.
In an embodiment, the light beam 1405 is substantially perpendicular or normal to the surface 1401 and the beam deflector 1404 reflects the specular reflection of the light beam from the surface 1401 toward the light beam steering assembly 1403, thereby preventing the specular reflection from reaching the detector. One protective cover. The direction of the specular reflection is along the line SR, which is normal to the surface 1401 of the sample. In an embodiment where the light beam 1405 is normal to the surface 1401, this line SR is the same as the direction of the illumination light beam 1405, where the common reference line or direction is referred to herein as the axis of the detection system 1400. In the case where the beam 1405 and the surface 1401 are at an oblique angle, the direction SR of the specular reflection will not be consistent with the incoming direction of the beam 1405; in this example, the line SR indicating the direction of the surface normal is called the detection system The main axis of the collection part of 1400.
The light scattered by the small particles is collected by the mirror 1406 and directed toward the aperture 1407 and the detector 1408. The light scattered by the large particles is collected by the lens 1409 and guided toward the aperture 1410 and the detector 1411. Note that some large particles also scatter the light collected and guided to detector 1408, and similarly, some small particles scatter the light collected and guided to detector 1411, but the intensity of this light is relatively low The respective detectors are designed to detect the intensity of the scattered light. In an embodiment, the detector 1411 may include an array of photosensitive elements, wherein each photosensitive element of the photosensitive element array is configured to detect a corresponding portion of an enlarged image of one of the illumination lines. In one embodiment, the inspection system may be configured to detect defects on an unpatterned wafer. US Patent 6,271,916, issued August 7, 2001 and incorporated herein by reference, further describes the detection system 1400.
FIG. 15 illustrates one of the detection systems 1500 configured to perform anomaly detection using both normal and oblique illumination beams. In this configuration, a laser system 1530 including one of the improved lasers described above can provide a laser beam 1501. A lens 1502 focuses the beam 1501 through a spatial filter 1503 and the lens 1504 collimates the beam and delivers it to a polarized beam splitter 1505. The beam splitter 1505 transmits a first polarized light component to the normal lighting channel and a second polarized light component to the oblique lighting channel, wherein the first component and the second component are orthogonal. In the normal illumination channel 1506, the first polarized light component is focused by the optical device 1507 and reflected by the mirror 1508 toward a surface of the sample 1509. The radiation scattered by the sample 1509 is collected by a parabolic mirror 1510 and focused onto a light multiplier tube 1511.
In the oblique illumination channel 1512, the second polarized light component is reflected by a beam splitter 1505 to a mirror 1513 (which reflects this light beam through the half-wave plate 1514) and focused to the sample 1509 by the optical device 1515. The radiation originating from the oblique illumination beam in the inclined channel 1512 and scattered by the sample 1509 is also collected by the parabolic mirror 1510 and focused on the light multiplier tube 1511. Note that the photomultiplier tube 1511 has a pinhole entrance. The pinhole and the illumination spot (from the normal and oblique illumination channels on the surface 1509) are preferably at the focal point of the parabolic mirror 1510.
The parabolic mirror 1510 collimates the scattered radiation from the sample 1509 into a collimated beam 1516. Then, the collimated light beam 1516 is focused by an objective lens 1517 and passed through an analyzer 1518 to the light multiplier tube 1511. Note that a curved mirror surface having a shape other than a parabolic shape can also be used. An instrument 1520 may provide relative motion between the light beam and the sample 1509 such that light spots are scanned across the surface of the sample 1509. US Patent 6,201,601, issued on March 13, 2001 and incorporated herein by reference, further describes the detection system 1500.
Other reduction masks, photomasks or wafer inspection systems can advantageously use the improved lasers described above. For example, other systems include the systems described in US Patents 5,563,702, 5,999,310, 6,201,601, 6,271,916, 7,352,457, 7,525,649, and 7,528,943. Still further systems include those described in US Publications 2007/0002465 and 2009/0180176. When used in a detection system, this improved laser can be advantageously combined with the coherence and speckle reduction devices and methods disclosed in published PCT application WO 2010/037106 and US patent application 13 / 073,986. This improved laser can also be advantageously combined with the methods and systems disclosed in the following applications: The United States of America, entitled "Optical peak power reduction of laser pulses and semiconductor and metrology systems using same", filed on June 13, 2011 Provisional application 61 / 496,446 and US patent application filed June 1, 2012 and published as US Publication 2012/0314286 on December 13, 2012 and titled "Semiconductor Inspection And Metrology System Using Laser Pulse Multiplier" 13 / 487,075. The patents, patent publications, and patent applications described in this paragraph are incorporated herein by reference.
Although some of the above embodiments are described as being converted to one of the output wavelengths of about 193.368 nanometers and about 1063.5 nanometer-based harmonic lengths, it should be understood that this way can be used to appropriately generate one of the fundamental harmonic length and one of the signal wavelengths. Other wavelengths within a few nanometers of 193.368 nanometers. These lasers and systems using them are within the scope of the present invention.
The improved laser will be significantly cheaper and have a longer life than the 8th harmonic laser, thereby providing a better holding cost compared to the 8th harmonic laser. Note that fundamental harmonic lasers operating at approximately 1064 nanometers are easily available at reasonable prices in various combinations of power and repetition rate. In fact, the improved laser as a whole can be constructed using components that are readily available and relatively inexpensive. Because the improved laser can be a high-repetition-rate mode-locked or Q-switched laser, compared to a low-repetition-rate laser, the improved laser can simplify the illumination of the reticle / mask / wafer inspection system optical instrument.
The various embodiments of the structure and method of the invention described above merely illustrate the principles of the invention and are not intended to limit the scope of the invention to the specific embodiments described.
For example, instead of generating exactly one wavelength that is twice as long as the fundamental harmonic length, it can be shifted by about 10 nanometers, 20 nanometers, or several hundred nanometers from double the fundamental harmonic length. By using a wavelength that is not exactly twice the fundamental harmonic length, an output wavelength that is slightly shifted from the fundamental harmonic length divided by 5.5 can be generated. For example, divide the fundamental harmonic length by a value between approximately 5.4 and 5.6, or in some embodiments divide the fundamental harmonic length by a value between approximately 5.49 and 5.51. Some embodiments down-convert the second harmonic frequency of the fundamental harmonic to produce a frequency of about half the fundamental harmonic frequency and about 1.5 times the fundamental harmonic frequency. Therefore, the present invention is limited only by the scope of the following patent applications and their equivalents.
100‧‧‧雷射系統 100‧‧‧laser system
101‧‧‧基諧波雷射 101‧‧‧ fundamental harmonic laser
102‧‧‧基諧波 102‧‧‧ fundamental harmonics
102’‧‧‧基諧波 102’‧‧‧based harmonics
103‧‧‧光學參數(OP)模組 103‧‧‧Optical Parameter (OP) Module
104‧‧‧未耗盡基諧波 104‧‧‧Undepleted fundamental harmonics
104’‧‧‧未耗盡基諧波/虛線 104’‧‧‧Undepleted fundamental harmonic / dashed line
105‧‧‧五次諧波(5ω)產生器模組 105‧‧‧Fifth harmonic (5ω) generator module
106‧‧‧5次諧波 106‧‧‧5th harmonic
107‧‧‧簡併輸出頻率/信號 107‧‧‧ degenerate output frequency / signal
108‧‧‧混頻模組 108‧‧‧ Mixing Module
109‧‧‧雷射輸出 109‧‧‧laser output
110‧‧‧基諧波雷射 110‧‧‧ fundamental harmonic laser
111‧‧‧基諧波 111‧‧‧ fundamental harmonics
112‧‧‧二次諧波產生器模組 112‧‧‧Second Harmonic Generator Module
113‧‧‧2次諧波 113‧‧‧2nd harmonic
113’‧‧‧2次諧波 113’‧‧‧2nd harmonic
114‧‧‧光學參數(OP)模組 114‧‧‧Optical Parameter (OP) Module
115‧‧‧2次諧波 115‧‧‧2nd harmonic
115’‧‧‧2次諧波 115’‧‧‧2nd harmonic
116‧‧‧五次諧波產生器模組 116‧‧‧Fifth harmonic generator module
117‧‧‧5次諧波 117‧‧‧5th harmonic
118‧‧‧混頻模組 118‧‧‧mixing module
119‧‧‧雷射輸出 119‧‧‧laser output
120‧‧‧輸出頻率 120‧‧‧output frequency
121‧‧‧未耗盡基諧波 121‧‧‧Undepleted fundamental harmonics
122‧‧‧基諧波雷射 122‧‧‧ fundamental harmonic laser
123‧‧‧基諧波 123‧‧‧Base Harmonics
124‧‧‧二次諧波產生器模組 124‧‧‧Second Harmonic Generator Module
125‧‧‧2次諧波 125‧‧‧2nd harmonic
125’‧‧‧2次諧波 125’‧‧‧2nd harmonic
126‧‧‧光學參數(OP)模組 126‧‧‧Optical Parameter (OP) Module
127‧‧‧未耗盡2次諧波 127‧‧‧ 2nd harmonic not depleted
127’‧‧‧未耗盡 2次諧波 127’‧‧‧ Undepleted 2nd harmonic
128‧‧‧四次諧波產生器模組 128‧‧‧Fourth Harmonic Generator Module
129‧‧‧信號/輸出頻率 129‧‧‧Signal / output frequency
130‧‧‧雷射系統 130‧‧‧laser system
131‧‧‧混頻模組 131‧‧‧mixing module
132‧‧‧雷射輸出/5.5ω輸出 132‧‧‧laser output / 5.5ω output
133‧‧‧4次諧波 133‧‧‧4th harmonic
140‧‧‧雷射系統 140‧‧‧laser system
200‧‧‧基諧波 200‧‧‧ fundamental harmonics
201‧‧‧二次諧波產生器 201‧‧‧Second Harmonic Generator
202‧‧‧2次諧波 202‧‧‧2nd harmonic
203‧‧‧未耗盡基諧波 203‧‧‧Undepleted fundamental harmonics
204‧‧‧四次諧波產生器 204‧‧‧Fourth harmonic generator
205‧‧‧4次諧波 205‧‧‧4th harmonic
206‧‧‧未耗盡2次諧波 206‧‧‧ 2nd harmonic without depletion
207‧‧‧五次諧波產生器 207‧‧‧Fifth harmonic generator
208‧‧‧未耗盡基諧波 208‧‧‧Undepleted fundamental harmonics
209‧‧‧未耗盡4次諧波 209‧‧‧Undepleted 4th harmonic
210‧‧‧5次諧波輸出 210‧‧‧5th harmonic output
211‧‧‧二次諧波產生器 211‧‧‧Second harmonic generator
212‧‧‧2次諧波 212‧‧‧2nd harmonic
213‧‧‧未耗盡基諧波 213‧‧‧Undepleted fundamental harmonics
214‧‧‧三次諧波產生器 214‧‧‧third harmonic generator
215‧‧‧3次諧波 215‧‧‧3rd harmonic
216‧‧‧未耗盡2次諧波 216‧‧‧2nd harmonic without depletion
217‧‧‧未耗盡基諧波 217‧‧‧Undepleted fundamental harmonics
218‧‧‧五次諧波產生器 218‧‧‧Fifth harmonic generator
219‧‧‧5次諧波輸出 219‧‧‧5th harmonic output
220‧‧‧未耗盡2次諧波 220‧‧‧ 2nd harmonic without depletion
221‧‧‧未耗盡3次諧波 221‧‧‧ Undepleted 3rd harmonic
222‧‧‧基諧波 222‧‧‧Base Harmonics
250‧‧‧五次諧波產生器模組 250‧‧‧Fifth harmonic generator module
260‧‧‧五次諧波產生器模組 260‧‧‧Fifth harmonic generator module
300‧‧‧五次諧波產生器模組 300‧‧‧Fifth harmonic generator module
301‧‧‧2次諧波 301‧‧‧2nd harmonic
302‧‧‧四次諧波產生器 302‧‧‧Fourth Harmonic Generator
303‧‧‧4次諧波 303‧‧‧4th harmonic
304‧‧‧未耗盡2次諧波 304‧‧‧ 2nd harmonic without depletion
305‧‧‧五次諧波產生器 305‧‧‧Fifth harmonic generator
306‧‧‧未耗盡基諧波 306‧‧‧Undepleted fundamental harmonics
307‧‧‧未耗盡4次諧波 307‧‧‧ 4th Harmonic
308‧‧‧基諧波/五次諧波輸出 308‧‧‧Base Harmonic / Fifth Harmonic Output
310‧‧‧五次諧波產生器模組 310‧‧‧Fifth harmonic generator module
311‧‧‧基諧波 311‧‧‧ fundamental harmonic
312‧‧‧2次諧波 312‧‧‧2nd harmonic
313‧‧‧三次諧波產生器 313‧‧‧third harmonic generator
314‧‧‧未耗盡基諧波 314‧‧‧Undepleted fundamental harmonics
315‧‧‧3次諧波 315‧‧‧3rd harmonic
317‧‧‧五次諧波產生器 317‧‧‧Fifth harmonic generator
318‧‧‧未耗盡2次諧波 318‧‧‧ 2nd harmonic not depleted
319‧‧‧未耗盡3次諧波 319‧‧‧Undepleted 3rd harmonic
320‧‧‧5次諧波輸出 320‧‧‧5th harmonic output
400‧‧‧雷射系統 400‧‧‧laser system
401‧‧‧基諧波雷射 401‧‧‧based harmonic laser
402‧‧‧基諧波 402‧‧‧base harmonic
402’‧‧‧基諧波 402’‧‧‧ fundamental harmonic
403‧‧‧光學參數(OP)模組 403‧‧‧Optical Parameter (OP) Module
404‧‧‧未耗盡基諧波 404‧‧‧Undepleted fundamental harmonic
404’‧‧‧未耗盡基諧波 404’‧‧‧ Undepleted fundamental harmonic
405‧‧‧輸出頻率 405‧‧‧Output frequency
406‧‧‧二次諧波產生器 406‧‧‧Second harmonic generator
407‧‧‧2次諧波 407‧‧‧2nd harmonic
408‧‧‧未耗盡基諧波 408‧‧‧Undepleted fundamental harmonics
409‧‧‧四次諧波產生器 409‧‧‧Fourth harmonic generator
410‧‧‧4次諧波 410‧‧‧4th harmonic
411‧‧‧未耗盡2次諧波 411‧‧‧Undepleted second harmonic
412‧‧‧混頻模組 412‧‧‧mixing module
413‧‧‧4.5次諧波 413‧‧‧4.5th harmonic
414‧‧‧未耗盡4次諧波及未耗盡光學參數(OP)信號 414‧‧‧ Undepleted 4th harmonic and undepleted optical parameter (OP) signal
416‧‧‧混頻模組 416‧‧‧mixing module
417‧‧‧雷射輸出 417‧‧‧laser output
418’‧‧‧未耗盡基諧波 418’‧‧‧ Undepleted fundamental harmonic
500‧‧‧基諧波雷射 500‧‧‧ fundamental harmonic laser
501‧‧‧放大器泵浦 501‧‧‧amplifier pump
502‧‧‧放大器 502‧‧‧amplifier
503‧‧‧種子雷射 503‧‧‧ Seed Laser
504‧‧‧光束分割器 504‧‧‧Beam Splitter
505‧‧‧鏡 505‧‧‧Mirror
506‧‧‧放大器 506‧‧‧amplifier
507‧‧‧放大器泵浦 507‧‧‧amplifier pump
508‧‧‧基諧波雷射輸出/基諧波 508‧‧‧based harmonic laser output / based harmonic
509‧‧‧基諧波雷射輸出/基諧波 509‧‧‧based harmonic laser output / based harmonic
600‧‧‧簡併光學參數放大器(OPA) 600‧‧‧Degenerate Optical Parameter Amplifier (OPA)
601‧‧‧種子雷射 601‧‧‧ Seed Laser
602‧‧‧光束組合器 602‧‧‧Beam combiner
603‧‧‧基諧波 603‧‧‧ fundamental harmonic
604‧‧‧非線性轉換器 604‧‧‧Nonlinear Converter
605‧‧‧光束分割器/稜鏡 605‧‧‧Beam Splitter / 稜鏡
606‧‧‧紅外光/輸出波長 606‧‧‧IR light / output wavelength
607‧‧‧未耗盡基諧波 607‧‧‧Undepleted fundamental harmonics
700‧‧‧非簡併光學參數放大器(OPA) 700‧‧‧ Non-degenerate optical parameter amplifier (OPA)
701‧‧‧種子雷射 701‧‧‧ seed laser
702‧‧‧光束組合器 702‧‧‧Beam combiner
703‧‧‧基諧波 703‧‧‧base harmonic
704‧‧‧非線性轉換器 704‧‧‧ Nonlinear Converter
705‧‧‧元件 705‧‧‧Element
706‧‧‧紅外光/波長/輸出光束 706‧‧‧IR light / wavelength / output beam
707‧‧‧波長 707‧‧‧wavelength
800‧‧‧光學檢測系統 800‧‧‧optical detection system
802‧‧‧第二透射透鏡 802‧‧‧Second transmission lens
804‧‧‧四分之一波板 804‧‧‧ quarter wave board
806‧‧‧中心路徑 806‧‧‧ center path
808‧‧‧第一反射透鏡 808‧‧‧First reflecting lens
809‧‧‧反射稜鏡 809‧‧‧Reflection 稜鏡
810‧‧‧透射稜鏡 810‧‧‧Transmission 稜鏡
811‧‧‧第二反射透鏡 811‧‧‧Second reflective lens
812‧‧‧基板 812‧‧‧ substrate
814‧‧‧參考集光透鏡 814‧‧‧Reference collecting lens
816‧‧‧參考偵測器 816‧‧‧Reference detector
851‧‧‧第一光學配置 851‧‧‧first optical configuration
852‧‧‧光源 852‧‧‧light source
854‧‧‧檢測光學器件 854‧‧‧ Detection Optics
856‧‧‧參考光學器件 856‧‧‧Reference Optics
857‧‧‧第二光學配置 857‧‧‧Second optical configuration
858‧‧‧透射光光學器件 858‧‧‧Transmitted Light Optics
860‧‧‧透射光偵測器/透射光偵測器配置 860‧‧‧Transmitted Light Detector / Transmitted Light Detector Configuration
862‧‧‧反射光光學器件 862‧‧‧Reflected Light Optics
864‧‧‧反射光偵測器/反射光偵測器配置 864‧‧‧Reflected Light Detector / Reflected Light Detector Configuration
870‧‧‧聲光裝置 870‧‧‧ sound and light device
872‧‧‧四分之一波板 872‧‧‧ quarter wave plate
874‧‧‧中繼透鏡 874‧‧‧ relay lens
876‧‧‧繞射光柵 876‧‧‧diffraction grating
880‧‧‧孔徑 880‧‧‧ aperture
882‧‧‧光束分割器立方體/偏光光束分割器/光束分割器 882‧‧‧beam splitter cube / polarized beam splitter / beam splitter
888‧‧‧望遠鏡 888‧‧‧ Telescope
890‧‧‧物鏡 890‧‧‧ Objective
896‧‧‧第一透射透鏡 896‧‧‧The first transmission lens
898‧‧‧球面像差校正器透鏡 898‧‧‧ spherical aberration corrector lens
900‧‧‧晶圓檢測系統 900‧‧‧ Wafer Inspection System
909‧‧‧照明源 909‧‧‧light source
915‧‧‧照明中繼光學器件 915‧‧‧lighting relay optics
920‧‧‧照明中繼光學器件 920‧‧‧lighting relay optics
930‧‧‧受檢測物體 930‧‧‧Detected object
940‧‧‧影像中繼光學器件 940‧‧‧Image Relay Optics
955‧‧‧影像中繼光學器件 955‧‧‧Image Relay Optics
960‧‧‧影像中繼光學器件 960‧‧‧Image Relay Optics
970‧‧‧感測器 970‧‧‧Sensor
980‧‧‧資料 980‧‧‧ Information
1000‧‧‧檢測系統 1000‧‧‧ Detection System
1001‧‧‧雷射源 1001‧‧‧Laser source
1002a‧‧‧元件/透鏡 1002a‧‧‧Element / Lens
1002b‧‧‧元件/透鏡 1002b‧‧‧Element / Lens
1003a‧‧‧元件/透鏡 1003a‧‧‧Element / Lens
1003b‧‧‧元件/鏡 1003b‧‧‧Element / Mirror
1004a‧‧‧元件/透鏡 1004a‧‧‧Element / Lens
1004b‧‧‧元件/透鏡 1004b‧‧‧Element / Lens
1005a‧‧‧元件/第一照明光瞳平面 1005a‧‧‧element / first illumination pupil plane
1005b‧‧‧元件/第二照明光瞳平面 1005b‧‧‧element / second illumination pupil plane
1006a‧‧‧元件/透鏡 1006a‧‧‧Element / Lens
1006b‧‧‧元件/透鏡 1006b‧‧‧Element / Lens
1007‧‧‧照明場平面/內場平面/照明場 1007‧‧‧Lighting Field Plane / Inner Field Plane / Lighting Field
1009‧‧‧中繼光學器件/透鏡 1009‧‧‧Relay Optics / Lens
1010‧‧‧光束分割器 1010‧‧‧Beam Splitter
1011‧‧‧物鏡光瞳平面 1011‧‧‧ Objective pupil plane
1012‧‧‧折反射物鏡 1012‧‧‧ Folding Reflective Objective
1013‧‧‧物鏡 1013‧‧‧ Objective
1014‧‧‧樣本 1014‧‧‧Sample
1015‧‧‧透鏡/中間影像形成光學器件 1015‧‧‧lens / intermediate image forming optics
1016‧‧‧內場/內部影像 1016‧‧‧ Infield / Internal Video
1017‧‧‧鏡 1017‧‧‧Mirror
1018a‧‧‧影像形成光學器件/透鏡 1018a‧‧‧Image forming optics / lens
1018b‧‧‧影像形成光學器件/透鏡 1018b‧‧‧Image forming optics / lens
1019a‧‧‧光瞳平面/成像光瞳 1019a‧‧‧ pupil plane / imaging pupil
1019b‧‧‧光瞳平面/成像光瞳 1019b‧‧‧ pupil plane / imaging pupil
1020a‧‧‧影像形成光學器件/透鏡 1020a‧‧‧Image forming optics / lens
1020b‧‧‧影像形成光學器件/透鏡 1020b‧‧‧Image forming optics / lens
1021a‧‧‧偵測器 1021a‧‧‧ Detector
1021b‧‧‧感測器 1021b‧‧‧Sensor
1100‧‧‧超寬頻紫外線(UV)顯微鏡成像系統 1100‧‧‧ultra-wideband ultraviolet (UV) microscope imaging system
1101A‧‧‧子區段 1101A‧‧‧Subsection
1101B‧‧‧子區段 1101B‧‧‧Subsection
1101C‧‧‧子區段 1101C‧‧‧Subsection
1102‧‧‧折反射物鏡區段 1102‧‧‧Folding Reflective Objective Section
1103‧‧‧變焦管透鏡/低功率透鏡群組 1103‧‧‧Zoom tube lens / low power lens group
1104‧‧‧折反射透鏡群組 1104‧‧‧Folding Reflective Lens Group
1105‧‧‧場透鏡群組 1105‧‧‧field lens group
1106‧‧‧聚焦透鏡群組 1106‧‧‧Focus lens group
1107‧‧‧光束分割器 1107‧‧‧Beam Splitter
1108‧‧‧紫外線(UV)光源 1108‧‧‧ultraviolet (UV) light source
1109‧‧‧物體/樣本 1109‧‧‧Object / Sample
1111‧‧‧折疊鏡群組 1111‧‧‧Folding mirror group
1112‧‧‧影像平面 1112‧‧‧Image plane
1113‧‧‧透鏡 1113‧‧‧Lens
1200‧‧‧折反射成像系統 1200‧‧‧ Folding Reflection Imaging System
1201‧‧‧雷射 1201‧‧‧Laser
1202‧‧‧調適光學器件 1202‧‧‧ Adapting Optics
1203‧‧‧孔徑與窗 1203‧‧‧Aperture and window
1204‧‧‧機械外殼 1204‧‧‧Mechanical housing
1205‧‧‧稜鏡 1205‧‧‧ 稜鏡
1206‧‧‧物鏡 1206‧‧‧ Objective
1208‧‧‧樣本 1208‧‧‧Sample
1209‧‧‧影像平面 1209‧‧‧Image plane
1300‧‧‧表面檢測設備 1300‧‧‧Surface inspection equipment
1301‧‧‧照明系統 1301‧‧‧lighting system
1302‧‧‧光束 1302‧‧‧Beam
1303‧‧‧透鏡 1303‧‧‧ lens
1304‧‧‧聚焦光束 1304‧‧‧ Focused Beam
1305‧‧‧照明線 1305‧‧‧lighting line
1310‧‧‧集光系統 1310‧‧‧light collection system
1311‧‧‧樣本表面 1311‧‧‧Surface
1312‧‧‧透鏡/平台(圖13B) 1312‧‧‧lens / platform (Figure 13B)
1314‧‧‧電荷耦合裝置(CCD) 1314‧‧‧ Charge Coupled Device (CCD)
1320‧‧‧雷射系統 1320‧‧‧laser system
1331‧‧‧集光系統 1331‧‧‧light collection system
1332‧‧‧集光系統 1332‧‧‧light collection system
1333‧‧‧集光系統 1333‧‧‧light collection system
1400‧‧‧表面檢測系統 1400‧‧‧Surface inspection system
1401‧‧‧表面 1401‧‧‧ surface
1402‧‧‧聚焦雷射光束 1402‧‧‧Focused laser beam
1403‧‧‧光束折疊組件/光束轉向組件 1403‧‧‧Beam Folding Kit / Beam Steering Kit
1404‧‧‧光束偏轉器 1404‧‧‧Beam Deflector
1405‧‧‧光束/照明光束 1405‧‧‧beam / illumination beam
1406‧‧‧鏡 1406‧‧‧Mirror
1407‧‧‧孔徑 1407‧‧‧Aperture
1408‧‧‧偵測器 1408‧‧‧ Detector
1409‧‧‧透鏡 1409‧‧‧Lens
1410‧‧‧孔徑 1410‧‧‧ Aperture
1411‧‧‧偵測器 1411‧‧‧ Detector
1421‧‧‧偏光光學器件 1421‧‧‧polarized optics
1422‧‧‧光束擴張器與孔徑 1422‧‧‧Beam Expander and Aperture
1423‧‧‧光束成形光學器件 1423‧‧‧Beam Shaping Optics
1430‧‧‧雷射系統 1430‧‧‧laser system
1500‧‧‧檢測系統 1500‧‧‧ Detection System
1501‧‧‧雷射光束 1501‧‧‧laser beam
1502‧‧‧透鏡 1502‧‧‧lens
1503‧‧‧空間濾波器 1503‧‧‧Spatial Filter
1504‧‧‧透鏡 1504‧‧‧ lens
1505‧‧‧偏光光束分割器 1505‧‧‧polarized beam splitter
1506‧‧‧法向照明通道 1506‧‧‧normal lighting channel
1507‧‧‧光學器件 1507‧‧‧Optics
1508‧‧‧鏡 1508‧‧‧Mirror
1509‧‧‧樣本 1509‧‧‧Sample
1510‧‧‧抛物面鏡 1510‧‧‧ Parabolic Mirror
1511‧‧‧光倍增管 1511‧‧‧Photomultiplier
1512‧‧‧傾斜照明通道 1512‧‧‧ Inclined lighting channel
1513‧‧‧鏡 1513‧‧‧Mirror
1514‧‧‧半波板 1514‧‧‧ Half-Wave Plate
1515‧‧‧光學器件 1515‧‧‧Optics
1516‧‧‧準直光束 1516‧‧‧ Collimated beam
1517‧‧‧物鏡 1517‧‧‧ Objective
1518‧‧‧檢偏鏡 1518‧‧‧analyzer
1520‧‧‧儀器 1520‧‧‧ Instrument
1530‧‧‧雷射系統 1530‧‧‧laser system
SR‧‧‧線 SR‧‧‧line
圖1A圖解說明用於使用一光學參數模組及一五次諧波產生器產生大約193.368奈米光之一例示性雷射之一方塊圖。FIG. 1A illustrates a block diagram of an exemplary laser for generating approximately 193.368 nanometers of light using an optical parameter module and a fifth harmonic generator.
圖1B圖解說明用於使用一光學參數模組及一五次諧波產生器產生大約193.368奈米光之另一例示性雷射之一方塊圖。 FIG. 1B illustrates a block diagram of another exemplary laser for generating approximately 193.368 nm light using an optical parameter module and a fifth harmonic generator.
圖1C圖解說明用於使用一光學參數模組及一四次諧波產生器模組產生大約193.368奈米光之又另一例示性雷射之一方塊圖。 FIG. 1C illustrates a block diagram of yet another exemplary laser for generating approximately 193.368 nanometers of light using an optical parameter module and a fourth harmonic generator module.
圖2A圖解說明一例示性五次諧波產生器模組。 FIG. 2A illustrates an exemplary fifth harmonic generator module.
圖2B圖解說明另一例示性五次諧波產生器模組。 FIG. 2B illustrates another exemplary fifth harmonic generator module.
圖3A圖解說明又另一例示性五次諧波產生器模組。 FIG. 3A illustrates yet another exemplary fifth harmonic generator module.
圖3B圖解說明另一例示性五次諧波產生器模組。 FIG. 3B illustrates another exemplary fifth harmonic generator module.
圖4圖解說明用於使用一光學參數模組及一四次諧波產生器產生大約193奈米光之又另一例示性雷射之一方塊圖。 FIG. 4 illustrates a block diagram of yet another exemplary laser for generating approximately 193 nm light using an optical parameter module and a fourth harmonic generator.
圖5圖解說明一例示性基諧波雷射之一方塊圖。 FIG. 5 illustrates a block diagram of an exemplary fundamental harmonic laser.
圖6圖解說明產生兩倍基諧波長或一半基諧波頻率之紅外光之一例示性簡併OP放大器。 FIG. 6 illustrates one exemplary degenerate OP amplifier of infrared light that generates twice the fundamental harmonic length or half the fundamental harmonic frequency.
圖7圖解說明產生並非確切兩倍基諧波長或一半基諧波頻率之紅外光之另一例示性OP放大器。 Figure 7 illustrates another exemplary OP amplifier that produces infrared light that is not exactly twice the fundamental harmonic length or half the fundamental harmonic frequency.
圖8圖解說明包含改良之雷射之一例示性檢測系統。 FIG. 8 illustrates an exemplary detection system including an improved laser.
圖9圖解說明同時偵測一感測器上之兩個影像(或信號)通道之一倍縮光罩、光罩或晶圓檢測系統。 FIG. 9 illustrates a reticle, photomask, or wafer inspection system that simultaneously detects one of two image (or signal) channels on a sensor.
圖10圖解說明包含多個物鏡及改良之雷射之一例示性檢測系統。 FIG. 10 illustrates one exemplary detection system including multiple objective lenses and a modified laser.
圖11圖解說明包含改良之雷射具有可調整放大率之一例示性檢測系統之光學器件。 FIG. 11 illustrates an optical device including an exemplary detection system with an improved laser having adjustable magnification.
圖12圖解說明具有暗場及明場模式且包含改良之雷射之一例示性檢測系統。 FIG. 12 illustrates one exemplary detection system having darkfield and brightfield modes and including an improved laser.
圖13A圖解說明包含改良之雷射之一表面檢測設備。圖13B圖解說明用於表面檢測設備之集光光學器件之一例示性陣列。 FIG. 13A illustrates a surface inspection device including an improved laser. FIG. 13B illustrates an exemplary array of light collection optics for a surface inspection device.
圖14圖解說明包含改良之雷射之一例示性表面檢測系統。 FIG. 14 illustrates an exemplary surface inspection system including an improved laser.
圖15圖解說明包含改良之雷射且使用法線及傾斜照明光束兩者之一檢測系統。 FIG. 15 illustrates a detection system that includes an improved laser and uses one of a normal and an oblique illumination beam.
Claims (1)
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| US13/797,939 US20130313440A1 (en) | 2012-05-22 | 2013-03-12 | Solid-State Laser And Inspection System Using 193nm Laser |
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- 2013-05-17 CN CN201711145150.1A patent/CN107887778B/en active Active
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| EP2853007A1 (en) | 2015-04-01 |
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| TW201349688A (en) | 2013-12-01 |
| US20170229829A1 (en) | 2017-08-10 |
| CN107887778A (en) | 2018-04-06 |
| US20130313440A1 (en) | 2013-11-28 |
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